21097560 has 96 divisors (see below), whose sum is σ = 69617520. Its totient is φ = 5111040.

The previous prime is 21097547. The next prime is 21097567. The reversal of 21097560 is 6579012.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21097567) 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, 13794 + ... + 15246.

Almost surely, 2^21097560 is an apocalyptic number.

21097560 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 21097560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34808760).

21097560 is an abundant number, since it is smaller than the sum of its proper divisors (48519960).

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

21097560 is a wasteful number, since it uses less digits than its factorization.

21097560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1489 (or 1474 counting only the distinct ones).

The product of its (nonzero) digits is 3780, while the sum is 30.

The square root of 21097560 is about 4593.2080292536. The cubic root of 21097560 is about 276.3189968455.

It can be divided in two parts, 2109 and 7560, that added together give a palindrome (9669).

The spelling of 21097560 in words is "twenty-one million, ninety-seven thousand, five hundred sixty".