21700530 has 24 divisors (see below), whose sum is σ = 56421612. Its totient is φ = 5786784.

The previous prime is 21700529. The next prime is 21700531. The reversal of 21700530 is 3500712.

It is an interprime number because it is at equal distance from previous prime (21700529) and next prime (21700531).

It can be written as a sum of positive squares in 2 ways, for example, as 19686969 + 2013561 = 4437^2 + 1419^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (21700531) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 120469 + ... + 120648.

Almost surely, 2^21700530 is an apocalyptic number.

21700530 is an abundant number, since it is smaller than the sum of its proper divisors (34721082).

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

21700530 is a wasteful number, since it uses less digits than its factorization.

21700530 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 241130 (or 241127 counting only the distinct ones).

The product of its (nonzero) digits is 210, while the sum is 18.

The square root of 21700530 is about 4658.3827665833. The cubic root of 21700530 is about 278.9267160205.

The spelling of 21700530 in words is "twenty-one million, seven hundred thousand, five hundred thirty".