21520710 has 24 divisors (see below), whose sum is σ = 55954080. Its totient is φ = 5738832.

The previous prime is 21520699. The next prime is 21520721. The reversal of 21520710 is 1702512.

It is an interprime number because it is at equal distance from previous prime (21520699) and next prime (21520721).

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

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 11 ways as a sum of consecutive naturals, for example, 119470 + ... + 119649.

It is an arithmetic number, because the mean of its divisors is an integer number (2331420).

Almost surely, 2^21520710 is an apocalyptic number.

21520710 is an abundant number, since it is smaller than the sum of its proper divisors (34433370).

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

21520710 is a wasteful number, since it uses less digits than its factorization.

21520710 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 239132 (or 239129 counting only the distinct ones).

The product of its (nonzero) digits is 140, while the sum is 18.

The square root of 21520710 is about 4639.0419269500. The cubic root of 21520710 is about 278.1541422142.

The spelling of 21520710 in words is "twenty-one million, five hundred twenty thousand, seven hundred ten".