21690520 has 16 divisors (see below), whose sum is σ = 48803760. Its totient is φ = 8676192.

The previous prime is 21690499. The next prime is 21690523. The reversal of 21690520 is 2509612.

It is a super-3 number, since 3×21690520³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21690523) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 271092 + ... + 271171.

It is an arithmetic number, because the mean of its divisors is an integer number (3050235).

Almost surely, 2^21690520 is an apocalyptic number.

21690520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21690520 is an abundant number, since it is smaller than the sum of its proper divisors (27113240).

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

21690520 is a wasteful number, since it uses less digits than its factorization.

21690520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 542274 (or 542270 counting only the distinct ones).

The product of its (nonzero) digits is 1080, while the sum is 25.

The square root of 21690520 is about 4657.3082354510. The cubic root of 21690520 is about 278.8838217403.

The spelling of 21690520 in words is "twenty-one million, six hundred ninety thousand, five hundred twenty".