21457936 has 10 divisors (see below), whose sum is σ = 41574782. Its totient is φ = 10728960.

The previous prime is 21457871. The next prime is 21457939. The reversal of 21457936 is 63975412.

It can be written as a sum of positive squares in only one way, i.e., 20647936 + 810000 = 4544^2 + 900^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21457895 and 21457904.

It is not an unprimeable number, because it can be changed into a prime (21457939) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 670545 + ... + 670576.

Almost surely, 2^21457936 is an apocalyptic number.

It is an amenable number.

21457936 is a deficient number, since it is larger than the sum of its proper divisors (20116846).

21457936 is a wasteful number, since it uses less digits than its factorization.

21457936 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1341129 (or 1341123 counting only the distinct ones).

The product of its digits is 45360, while the sum is 37.

The square root of 21457936 is about 4632.2711492312. The cubic root of 21457936 is about 277.8834285166.

The spelling of 21457936 in words is "twenty-one million, four hundred fifty-seven thousand, nine hundred thirty-six".