21377138 has 4 divisors (see below), whose sum is σ = 32065710. Its totient is φ = 10688568.

The previous prime is 21377131. The next prime is 21377159. The reversal of 21377138 is 83177312.

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., 13520329 + 7856809 = 3677^2 + 2803^2 .

It is not an unprimeable number, because it can be changed into a prime (21377131) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5344283 + ... + 5344286.

Almost surely, 2^21377138 is an apocalyptic number.

21377138 is a deficient number, since it is larger than the sum of its proper divisors (10688572).

21377138 is a wasteful number, since it uses less digits than its factorization.

21377138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10688571.

The product of its digits is 7056, while the sum is 32.

The square root of 21377138 is about 4623.5417160441. The cubic root of 21377138 is about 277.5342078329.

The spelling of 21377138 in words is "twenty-one million, three hundred seventy-seven thousand, one hundred thirty-eight".