21260138 has 4 divisors (see below), whose sum is σ = 31890210. Its totient is φ = 10630068.

The previous prime is 21260137. The next prime is 21260153. The reversal of 21260138 is 83106212.

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., 20043529 + 1216609 = 4477^2 + 1103^2 .

It is not an unprimeable number, because it can be changed into a prime (21260137) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5315033 + ... + 5315036.

Almost surely, 2^21260138 is an apocalyptic number.

21260138 is a deficient number, since it is larger than the sum of its proper divisors (10630072).

21260138 is a wasteful number, since it uses less digits than its factorization.

21260138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10630071.

The product of its (nonzero) digits is 576, while the sum is 23.

The square root of 21260138 is about 4610.8717180160. The cubic root of 21260138 is about 277.0269537213.

The spelling of 21260138 in words is "twenty-one million, two hundred sixty thousand, one hundred thirty-eight".