21366972 has 72 divisors (see below), whose sum is σ = 59754240. Its totient is φ = 6383520.

The previous prime is 21366971. The next prime is 21366973. The reversal of 21366972 is 27966312.

It is an interprime number because it is at equal distance from previous prime (21366971) and next prime (21366973).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21366971) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 30943 + ... + 31625.

It is an arithmetic number, because the mean of its divisors is an integer number (829920).

Almost surely, 2^21366972 is an apocalyptic number.

21366972 is a gapful number since it is divisible by the number (22) 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 21366972, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29877120).

21366972 is an abundant number, since it is smaller than the sum of its proper divisors (38387268).

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

21366972 is a wasteful number, since it uses less digits than its factorization.

21366972 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 783 (or 778 counting only the distinct ones).

The product of its digits is 27216, while the sum is 36.

The square root of 21366972 is about 4622.4422116453. The cubic root of 21366972 is about 277.4902066181.

The spelling of 21366972 in words is "twenty-one million, three hundred sixty-six thousand, nine hundred seventy-two".