21157070 has 64 divisors (see below), whose sum is σ = 44789760. Its totient is φ = 7113600.

The previous prime is 21157067. The next prime is 21157091. The reversal of 21157070 is 7075112.

It is a happy number.

It is a super-2 number, since 2×21157070² = 895243221969800, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 110675 + ... + 110865.

It is an arithmetic number, because the mean of its divisors is an integer number (699840).

Almost surely, 2^21157070 is an apocalyptic number.

21157070 is an abundant number, since it is smaller than the sum of its proper divisors (23632690).

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

21157070 is a wasteful number, since it uses less digits than its factorization.

21157070 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 281.

The product of its (nonzero) digits is 490, while the sum is 23.

The square root of 21157070 is about 4599.6815107135. The cubic root of 21157070 is about 276.5785577726.

The spelling of 21157070 in words is "twenty-one million, one hundred fifty-seven thousand, seventy".