21139689 has 16 divisors (see below), whose sum is σ = 28753920. Its totient is φ = 13812240.

The previous prime is 21139667. The next prime is 21139709. The reversal of 21139689 is 98693112.

It is not a de Polignac number, because 21139689 - 2¹² = 21135593 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21139649) 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, 45034 + ... + 45500.

It is an arithmetic number, because the mean of its divisors is an integer number (1797120).

Almost surely, 2^21139689 is an apocalyptic number.

It is an amenable number.

21139689 is a deficient number, since it is larger than the sum of its proper divisors (7614231).

21139689 is a wasteful number, since it uses less digits than its factorization.

21139689 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 740.

The product of its digits is 23328, while the sum is 39.

The square root of 21139689 is about 4597.7917525699. The cubic root of 21139689 is about 276.5027985595.

The spelling of 21139689 in words is "twenty-one million, one hundred thirty-nine thousand, six hundred eighty-nine".