21308070 has 32 divisors (see below), whose sum is σ = 58445568. Its totient is φ = 4870368.

The previous prime is 21308059. The next prime is 21308081. The reversal of 21308070 is 7080312.

21308070 = 666² + 667² + ... + 710².

It is an interprime number because it is at equal distance from previous prime (21308059) and next prime (21308081).

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 50524 + ... + 50943.

It is an arithmetic number, because the mean of its divisors is an integer number (1826424).

Almost surely, 2^21308070 is an apocalyptic number.

21308070 is an abundant number, since it is smaller than the sum of its proper divisors (37137498).

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

21308070 is a wasteful number, since it uses less digits than its factorization.

21308070 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 101484.

The product of its (nonzero) digits is 336, while the sum is 21.

The square root of 21308070 is about 4616.0665073198. The cubic root of 21308070 is about 277.2349876399.

Adding to 21308070 its reverse (7080312), we get a palindrome (28388382).

The spelling of 21308070 in words is "twenty-one million, three hundred eight thousand, seventy".