21891672 has 96 divisors (see below), whose sum is σ = 65482560. Its totient is φ = 6552000.

The previous prime is 21891637. The next prime is 21891677. The reversal of 21891672 is 27619812.

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 (21891677) 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, 103647 + ... + 103857.

It is an arithmetic number, because the mean of its divisors is an integer number (682110).

Almost surely, 2^21891672 is an apocalyptic number.

21891672 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 21891672, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32741280).

21891672 is an abundant number, since it is smaller than the sum of its proper divisors (43590888).

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

21891672 is a wasteful number, since it uses less digits than its factorization.

21891672 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 365 (or 358 counting only the distinct ones).

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

The square root of 21891672 is about 4678.8537057702. The cubic root of 21891672 is about 279.7432680759.

The spelling of 21891672 in words is "twenty-one million, eight hundred ninety-one thousand, six hundred seventy-two".