21791370 has 16 divisors (see below), whose sum is σ = 52299360. Its totient is φ = 5811024.

The previous prime is 21791353. The next prime is 21791477. The reversal of 21791370 is 7319712.

It is a Harshad number since it is a multiple of its sum of digits (30), and also a Moran number because the ratio is a prime number: 726379 = 21791370 / (2 + 1 + 7 + 9 + 1 + 3 + 7 + 0).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 363160 + ... + 363219.

It is an arithmetic number, because the mean of its divisors is an integer number (3268710).

Almost surely, 2^21791370 is an apocalyptic number.

21791370 is an abundant number, since it is smaller than the sum of its proper divisors (30507990).

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

21791370 is a wasteful number, since it uses less digits than its factorization.

21791370 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 726389.

The product of its (nonzero) digits is 2646, while the sum is 30.

The square root of 21791370 is about 4668.1227490288. The cubic root of 21791370 is about 279.3153767232.

The spelling of 21791370 in words is "twenty-one million, seven hundred ninety-one thousand, three hundred seventy".