21905924 has 12 divisors (see below), whose sum is σ = 39371724. Its totient is φ = 10656864.

The previous prime is 21905899. The next prime is 21905927. The reversal of 21905924 is 42950912.

It can be written as a sum of positive squares in 2 ways, for example, as 11343424 + 10562500 = 3368^2 + 3250^2 .

It is not an unprimeable number, because it can be changed into a prime (21905927) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 73859 + ... + 74154.

It is an arithmetic number, because the mean of its divisors is an integer number (3280977).

Almost surely, 2^21905924 is an apocalyptic number.

It is an amenable number.

21905924 is a deficient number, since it is larger than the sum of its proper divisors (17465800).

21905924 is a wasteful number, since it uses less digits than its factorization.

21905924 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 148054 (or 148052 counting only the distinct ones).

The product of its (nonzero) digits is 6480, while the sum is 32.

The square root of 21905924 is about 4680.3764805836. The cubic root of 21905924 is about 279.8039614175.

The spelling of 21905924 in words is "twenty-one million, nine hundred five thousand, nine hundred twenty-four".