21257670 has 48 divisors (see below), whose sum is σ = 59352048. Its totient is φ = 4858560.

The previous prime is 21257669. The next prime is 21257671. The reversal of 21257670 is 7675212.

It is an interprime number because it is at equal distance from previous prime (21257669) and next prime (21257671).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a zygodrome in base 9.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21257671) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5761 + ... + 8700.

It is an arithmetic number, because the mean of its divisors is an integer number (1236501).

Almost surely, 2^21257670 is an apocalyptic number.

21257670 is an abundant number, since it is smaller than the sum of its proper divisors (38094378).

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

21257670 is a wasteful number, since it uses less digits than its factorization.

21257670 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14485 (or 14478 counting only the distinct ones).

The product of its (nonzero) digits is 5880, while the sum is 30.

The square root of 21257670 is about 4610.6040818964. The cubic root of 21257670 is about 277.0162336752.

The spelling of 21257670 in words is "twenty-one million, two hundred fifty-seven thousand, six hundred seventy".