21257416 has 16 divisors (see below), whose sum is σ = 39916800. Its totient is φ = 10612944.

The previous prime is 21257407. The next prime is 21257417. The reversal of 21257416 is 61475212.

It is not an unprimeable number, because it can be changed into a prime (21257417) 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, 5365 + ... + 8443.

It is an arithmetic number, because the mean of its divisors is an integer number (2494800).

Almost surely, 2^21257416 is an apocalyptic number.

It is an amenable number.

21257416 is a deficient number, since it is larger than the sum of its proper divisors (18659384).

21257416 is a wasteful number, since it uses less digits than its factorization.

21257416 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3948 (or 3944 counting only the distinct ones).

The product of its digits is 3360, while the sum is 28.

The square root of 21257416 is about 4610.5765366167. The cubic root of 21257416 is about 277.0151303495.

The spelling of 21257416 in words is "twenty-one million, two hundred fifty-seven thousand, four hundred sixteen".