21391170 has 16 divisors (see below), whose sum is σ = 51338880. Its totient is φ = 5704304.

The previous prime is 21391133. The next prime is 21391187. The reversal of 21391170 is 7119312.

It is a self number, because there is not a number n which added to its sum of digits gives 21391170.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 356490 + ... + 356549.

It is an arithmetic number, because the mean of its divisors is an integer number (3208680).

Almost surely, 2^21391170 is an apocalyptic number.

21391170 is an abundant number, since it is smaller than the sum of its proper divisors (29947710).

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

21391170 is a wasteful number, since it uses less digits than its factorization.

21391170 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 713049.

The product of its (nonzero) digits is 378, while the sum is 24.

The square root of 21391170 is about 4625.0589185436. The cubic root of 21391170 is about 277.5949192375.

The spelling of 21391170 in words is "twenty-one million, three hundred ninety-one thousand, one hundred seventy".