21791268 has 96 divisors (see below), whose sum is σ = 59512320. Its totient is φ = 6975072.

The previous prime is 21791257. The next prime is 21791279. The reversal of 21791268 is 86219712.

It is an interprime number because it is at equal distance from previous prime (21791257) and next prime (21791279).

It is a super-2 number, since 2×21791268² = 949718722095648, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 411130 + ... + 411182.

It is an arithmetic number, because the mean of its divisors is an integer number (619920).

Almost surely, 2^21791268 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21791268, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29756160).

21791268 is an abundant number, since it is smaller than the sum of its proper divisors (37721052).

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

21791268 is an equidigital number, since it uses as much as digits as its factorization.

21791268 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 125 (or 105 counting only the distinct ones).

The product of its digits is 12096, while the sum is 36.

The square root of 21791268 is about 4668.1118238534. Note that the first 3 decimals coincide. The cubic root of 21791268 is about 279.3149409205.

The spelling of 21791268 in words is "twenty-one million, seven hundred ninety-one thousand, two hundred sixty-eight".