21919965 has 16 divisors (see below), whose sum is σ = 35278848. Its totient is φ = 11621696.

The previous prime is 21919957. The next prime is 21919979. The reversal of 21919965 is 56991912.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21919965 - 2³ = 21919957 is a prime.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

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, 1629 + ... + 6818.

It is an arithmetic number, because the mean of its divisors is an integer number (2204928).

Almost surely, 2^21919965 is an apocalyptic number.

It is an amenable number.

21919965 is a deficient number, since it is larger than the sum of its proper divisors (13358883).

21919965 is a wasteful number, since it uses less digits than its factorization.

21919965 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8628.

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

The square root of 21919965 is about 4681.8762264716. The cubic root of 21919965 is about 279.8637304602.

The spelling of 21919965 in words is "twenty-one million, nine hundred nineteen thousand, nine hundred sixty-five".