21172398 has 24 divisors (see below), whose sum is σ = 45689784. Its totient is φ = 6502080.

The previous prime is 21172381. The next prime is 21172423. The reversal of 21172398 is 89327112.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 40378 + ... + 40898.

It is an arithmetic number, because the mean of its divisors is an integer number (1903741).

Almost surely, 2^21172398 is an apocalyptic number.

21172398 is an abundant number, since it is smaller than the sum of its proper divisors (24517386).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21172398 is an equidigital number, since it uses as much as digits as its factorization.

21172398 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1060 (or 539 counting only the distinct ones).

The product of its digits is 6048, while the sum is 33.

The square root of 21172398 is about 4601.3474113568. The cubic root of 21172398 is about 276.6453340756.

The spelling of 21172398 in words is "twenty-one million, one hundred seventy-two thousand, three hundred ninety-eight".