21555480 has 64 divisors (see below), whose sum is σ = 65007360. Its totient is φ = 5717888.

The previous prime is 21555467. The next prime is 21555491. The reversal of 21555480 is 8455512.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 31219 + ... + 31901.

It is an arithmetic number, because the mean of its divisors is an integer number (1015740).

Almost surely, 2^21555480 is an apocalyptic number.

21555480 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 21555480, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32503680).

21555480 is an abundant number, since it is smaller than the sum of its proper divisors (43451880).

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

21555480 is a wasteful number, since it uses less digits than its factorization.

21555480 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 960 (or 956 counting only the distinct ones).

The product of its (nonzero) digits is 8000, while the sum is 30.

The square root of 21555480 is about 4642.7879555284. The cubic root of 21555480 is about 278.3038618043.

The spelling of 21555480 in words is "twenty-one million, five hundred fifty-five thousand, four hundred eighty".