21897129 has 16 divisors (see below), whose sum is σ = 30334464. Its totient is φ = 14035200.

The previous prime is 21897097. The next prime is 21897133. The reversal of 21897129 is 92179812.

It is not a de Polignac number, because 21897129 - 2⁵ = 21897097 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21897149) 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, 15409 + ... + 16769.

It is an arithmetic number, because the mean of its divisors is an integer number (1895904).

Almost surely, 2^21897129 is an apocalyptic number.

It is an amenable number.

21897129 is a deficient number, since it is larger than the sum of its proper divisors (8437335).

21897129 is a wasteful number, since it uses less digits than its factorization.

21897129 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1568.

The product of its digits is 18144, while the sum is 39.

The square root of 21897129 is about 4679.4368250891. The cubic root of 21897129 is about 279.7665102809.

The spelling of 21897129 in words is "twenty-one million, eight hundred ninety-seven thousand, one hundred twenty-nine".