21919161 has 16 divisors (see below), whose sum is σ = 33269760. Its totient is φ = 12706320.

The previous prime is 21919159. The next prime is 21919169. The reversal of 21919161 is 16191912.

It is not a de Polignac number, because 21919161 - 2¹ = 21919159 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21919169) 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, 13681 + ... + 15198.

It is an arithmetic number, because the mean of its divisors is an integer number (2079360).

Almost surely, 2^21919161 is an apocalyptic number.

It is an amenable number.

21919161 is a deficient number, since it is larger than the sum of its proper divisors (11350599).

21919161 is a wasteful number, since it uses less digits than its factorization.

21919161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28916.

The product of its digits is 972, while the sum is 30.

The square root of 21919161 is about 4681.7903626711. The cubic root of 21919161 is about 279.8603087213.

The spelling of 21919161 in words is "twenty-one million, nine hundred nineteen thousand, one hundred sixty-one".