21965139 has 24 divisors (see below), whose sum is σ = 38394720. Its totient is φ = 11812608.

The previous prime is 21965117. The next prime is 21965149. The reversal of 21965139 is 93156912.

It is not a de Polignac number, because 21965139 - 2¹⁵ = 21932371 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21965149) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 9184 + ... + 11325.

It is an arithmetic number, because the mean of its divisors is an integer number (1599780).

Almost surely, 2^21965139 is an apocalyptic number.

21965139 is a deficient number, since it is larger than the sum of its proper divisors (16429581).

21965139 is a wasteful number, since it uses less digits than its factorization.

21965139 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20539 (or 20536 counting only the distinct ones).

The product of its digits is 14580, while the sum is 36.

The square root of 21965139 is about 4686.6980914072. The cubic root of 21965139 is about 280.0558519536.

The spelling of 21965139 in words is "twenty-one million, nine hundred sixty-five thousand, one hundred thirty-nine".