21615328 has 24 divisors (see below), whose sum is σ = 48634992. Its totient is φ = 9263616.

The previous prime is 21615301. The next prime is 21615337. The reversal of 21615328 is 82351612.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a junction number, because it is equal to n+sod(n) for n = 21615296 and 21615305.

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 48025 + ... + 48472.

It is an arithmetic number, because the mean of its divisors is an integer number (2026458).

Almost surely, 2^21615328 is an apocalyptic number.

21615328 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21615328 is an abundant number, since it is smaller than the sum of its proper divisors (27019664).

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

21615328 is an equidigital number, since it uses as much as digits as its factorization.

21615328 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 96514 (or 96506 counting only the distinct ones).

The product of its digits is 2880, while the sum is 28.

The square root of 21615328 is about 4649.2287532450. The cubic root of 21615328 is about 278.5611906196.

The spelling of 21615328 in words is "twenty-one million, six hundred fifteen thousand, three hundred twenty-eight".