21911840 has 24 divisors (see below), whose sum is σ = 51767100. Its totient is φ = 8764672.

The previous prime is 21911839. The next prime is 21911887. The reversal of 21911840 is 4811912.

It can be written as a sum of positive squares in 2 ways, for example, as 19963024 + 1948816 = 4468^2 + 1396^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 68315 + ... + 68634.

Almost surely, 2^21911840 is an apocalyptic number.

21911840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21911840 is an abundant number, since it is smaller than the sum of its proper divisors (29855260).

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

21911840 is a wasteful number, since it uses less digits than its factorization.

21911840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 136964 (or 136956 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 26.

The square root of 21911840 is about 4681.0084383603. The cubic root of 21911840 is about 279.8291474698.

The spelling of 21911840 in words is "twenty-one million, nine hundred eleven thousand, eight hundred forty".