21863772 has 72 divisors (see below), whose sum is σ = 64393056. Its totient is φ = 6125184.

The previous prime is 21863771. The next prime is 21863797. The reversal of 21863772 is 27736812.

21863772 is a `hidden beast` number, since 2 + 18 + 637 + 7 + 2 = 666.

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 (21863771) 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, 12538 + ... + 14174.

It is an arithmetic number, because the mean of its divisors is an integer number (894348).

Almost surely, 2^21863772 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 21863772, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32196528).

21863772 is an abundant number, since it is smaller than the sum of its proper divisors (42529284).

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

21863772 is a wasteful number, since it uses less digits than its factorization.

21863772 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1707 (or 1702 counting only the distinct ones).

The product of its digits is 28224, while the sum is 36.

The square root of 21863772 is about 4675.8712557127. The cubic root of 21863772 is about 279.6243772762.

The spelling of 21863772 in words is "twenty-one million, eight hundred sixty-three thousand, seven hundred seventy-two".