21157210 has 8 divisors (see below), whose sum is σ = 38082996. Its totient is φ = 8462880.

The previous prime is 21157207. The next prime is 21157243. The reversal of 21157210 is 1275112.

It can be written as a sum of positive squares in 2 ways, for example, as 20894041 + 263169 = 4571^2 + 513^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1057851 + ... + 1057870.

Almost surely, 2^21157210 is an apocalyptic number.

21157210 is a deficient number, since it is larger than the sum of its proper divisors (16925786).

21157210 is a wasteful number, since it uses less digits than its factorization.

21157210 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2115728.

The product of its (nonzero) digits is 140, while the sum is 19.

The square root of 21157210 is about 4599.6967291333. The cubic root of 21157210 is about 276.5791678273.

The spelling of 21157210 in words is "twenty-one million, one hundred fifty-seven thousand, two hundred ten".