21765480 has 96 divisors (see below), whose sum is σ = 71820000. Its totient is φ = 5272960.

The previous prime is 21765479. The next prime is 21765481. The reversal of 21765480 is 8456712.

It is an interprime number because it is at equal distance from previous prime (21765479) and next prime (21765481).

It is a super-2 number, since 2×21765480² = 947472239260800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21765481) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 13771 + ... + 15269.

It is an arithmetic number, because the mean of its divisors is an integer number (748125).

Almost surely, 2^21765480 is an apocalyptic number.

21765480 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21765480, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35910000).

21765480 is an abundant number, since it is smaller than the sum of its proper divisors (50054520).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21765480 is a wasteful number, since it uses less digits than its factorization.

21765480 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1535 (or 1520 counting only the distinct ones).

The product of its (nonzero) digits is 13440, while the sum is 33.

The square root of 21765480 is about 4665.3488615537. The cubic root of 21765480 is about 279.2047160830.

The spelling of 21765480 in words is "twenty-one million, seven hundred sixty-five thousand, four hundred eighty".