21965919 has 16 divisors (see below), whose sum is σ = 31257600. Its totient is φ = 13680576.

The previous prime is 21965899. The next prime is 21965927. The reversal of 21965919 is 91956912.

It is a happy number.

It is a de Polignac number, because none of the positive numbers 2^k-21965919 is a prime.

It is a super-2 number, since 2×21965919² = 965003195029122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21965959) 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, 1522 + ... + 6800.

It is an arithmetic number, because the mean of its divisors is an integer number (1953600).

Almost surely, 2^21965919 is an apocalyptic number.

21965919 is a deficient number, since it is larger than the sum of its proper divisors (9291681).

21965919 is a wasteful number, since it uses less digits than its factorization.

21965919 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5374.

The product of its digits is 43740, while the sum is 42.

The square root of 21965919 is about 4686.7813049043. The cubic root of 21965919 is about 280.0591669183.

The spelling of 21965919 in words is "twenty-one million, nine hundred sixty-five thousand, nine hundred nineteen".