21598157 has 4 divisors (see below), whose sum is σ = 24683616. Its totient is φ = 18512700.

The previous prime is 21598153. The next prime is 21598163. The reversal of 21598157 is 75189512.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21598157 - 2² = 21598153 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21598157.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21598151) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1542719 + ... + 1542732.

It is an arithmetic number, because the mean of its divisors is an integer number (6170904).

Almost surely, 2^21598157 is an apocalyptic number.

It is an amenable number.

21598157 is a deficient number, since it is larger than the sum of its proper divisors (3085459).

21598157 is an equidigital number, since it uses as much as digits as its factorization.

21598157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3085458.

The product of its digits is 25200, while the sum is 38.

The square root of 21598157 is about 4647.3817359886. The cubic root of 21598157 is about 278.4874090061.

The spelling of 21598157 in words is "twenty-one million, five hundred ninety-eight thousand, one hundred fifty-seven".