21053138 has 4 divisors (see below), whose sum is σ = 31579710. Its totient is φ = 10526568.

The previous prime is 21053129. The next prime is 21053173. The reversal of 21053138 is 83135012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 11950849 + 9102289 = 3457^2 + 3017^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5263283 + ... + 5263286.

Almost surely, 2^21053138 is an apocalyptic number.

21053138 is a deficient number, since it is larger than the sum of its proper divisors (10526572).

21053138 is a wasteful number, since it uses less digits than its factorization.

21053138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10526571.

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 21053138 is about 4588.3698630341. The cubic root of 21053138 is about 276.1249259429.

The spelling of 21053138 in words is "twenty-one million, fifty-three thousand, one hundred thirty-eight".