21910812 has 96 divisors (see below), whose sum is σ = 66576384. Its totient is φ = 5438400.

The previous prime is 21910799. The next prime is 21910829. The reversal of 21910812 is 21801912.

It is a hoax number, since the sum of its digits (24) coincides with the sum of the digits of its distinct prime factors.

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, 20737 + ... + 21767.

It is an arithmetic number, because the mean of its divisors is an integer number (693504).

Almost surely, 2^21910812 is an apocalyptic number.

21910812 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 21910812, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33288192).

21910812 is an abundant number, since it is smaller than the sum of its proper divisors (44665572).

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

21910812 is a wasteful number, since it uses less digits than its factorization.

21910812 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1079 (or 1077 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 24.

The square root of 21910812 is about 4680.8986316732. The cubic root of 21910812 is about 279.8247713142.

Subtracting from 21910812 its reverse (21801912), we obtain a square (108900 = 330²).

It can be divided in two parts, 21910 and 812, that added together give a palindrome (22722).

The spelling of 21910812 in words is "twenty-one million, nine hundred ten thousand, eight hundred twelve".