21231538 has 32 divisors (see below), whose sum is σ = 35555760. Its totient is φ = 9461760.

The previous prime is 21231523. The next prime is 21231547. The reversal of 21231538 is 83513212.

It can be written as a sum of positive squares in 8 ways, for example, as 6692569 + 14538969 = 2587^2 + 3813^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 59970 + ... + 60322.

Almost surely, 2^21231538 is an apocalyptic number.

21231538 is a deficient number, since it is larger than the sum of its proper divisors (14324222).

21231538 is a wasteful number, since it uses less digits than its factorization.

21231538 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 462.

The product of its digits is 1440, while the sum is 25.

The square root of 21231538 is about 4607.7693084615. The cubic root of 21231538 is about 276.9026753449.

The spelling of 21231538 in words is "twenty-one million, two hundred thirty-one thousand, five hundred thirty-eight".