21139613 has 16 divisors (see below), whose sum is σ = 24330240. Its totient is φ = 18188400.

The previous prime is 21139597. The next prime is 21139621. The reversal of 21139613 is 31693112.

It is a cyclic number.

It is not a de Polignac number, because 21139613 - 2⁴ = 21139597 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21139213) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15368 + ... + 16686.

It is an arithmetic number, because the mean of its divisors is an integer number (1520640).

Almost surely, 2^21139613 is an apocalyptic number.

It is an amenable number.

21139613 is a deficient number, since it is larger than the sum of its proper divisors (3190627).

21139613 is a wasteful number, since it uses less digits than its factorization.

21139613 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1408.

The product of its digits is 972, while the sum is 26.

The square root of 21139613 is about 4597.7834877254. The cubic root of 21139613 is about 276.5024672043.

The spelling of 21139613 in words is "twenty-one million, one hundred thirty-nine thousand, six hundred thirteen".