21355968 has 28 divisors (see below), whose sum is σ = 56504840. Its totient is φ = 7118592.

The previous prime is 21355967. The next prime is 21355969. The reversal of 21355968 is 86955312.

It is an interprime number because it is at equal distance from previous prime (21355967) and next prime (21355969).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21355963) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 55423 + ... + 55806.

It is an arithmetic number, because the mean of its divisors is an integer number (2018030).

Almost surely, 2^21355968 is an apocalyptic number.

It is an amenable number.

21355968 is an abundant number, since it is smaller than the sum of its proper divisors (35148872).

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

21355968 is a wasteful number, since it uses less digits than its factorization.

21355968 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 111244 (or 111234 counting only the distinct ones).

The product of its digits is 64800, while the sum is 39.

The square root of 21355968 is about 4621.2517784687. The cubic root of 21355968 is about 277.4425625787.

The spelling of 21355968 in words is "twenty-one million, three hundred fifty-five thousand, nine hundred sixty-eight".