21898591 has 8 divisors (see below), whose sum is σ = 25727184. Its totient is φ = 18376320.

The previous prime is 21898577. The next prime is 21898603. The reversal of 21898591 is 19589812.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21898591 - 2⁵ = 21898559 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21898501) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 76426 + ... + 76711.

It is an arithmetic number, because the mean of its divisors is an integer number (3215898).

Almost surely, 2^21898591 is an apocalyptic number.

21898591 is a deficient number, since it is larger than the sum of its proper divisors (3828593).

21898591 is a wasteful number, since it uses less digits than its factorization.

21898591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 153161.

The product of its digits is 51840, while the sum is 43.

The square root of 21898591 is about 4679.5930378613. The cubic root of 21898591 is about 279.7727365087.

The spelling of 21898591 in words is "twenty-one million, eight hundred ninety-eight thousand, five hundred ninety-one".