21615968 has 24 divisors (see below), whose sum is σ = 46425960. Its totient is φ = 9825280.

The previous prime is 21615961. The next prime is 21615973. The reversal of 21615968 is 86951612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21615961) 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 3 ways as a sum of consecutive naturals, for example, 30353 + ... + 31056.

It is an arithmetic number, because the mean of its divisors is an integer number (1934415).

Almost surely, 2^21615968 is an apocalyptic number.

It is an amenable number.

21615968 is an abundant number, since it is smaller than the sum of its proper divisors (24809992).

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

21615968 is a wasteful number, since it uses less digits than its factorization.

21615968 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61430 (or 61422 counting only the distinct ones).

The product of its digits is 25920, while the sum is 38.

The square root of 21615968 is about 4649.2975813557. The cubic root of 21615968 is about 278.5639398632.

The spelling of 21615968 in words is "twenty-one million, six hundred fifteen thousand, nine hundred sixty-eight".