20520840 has 32 divisors (see below), whose sum is σ = 61562880. Its totient is φ = 5472192.

The previous prime is 20520833. The next prime is 20520859. The reversal of 20520840 is 4802502.

It is a super-2 number, since 2×20520840² = 842209748611200, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 85384 + ... + 85623.

It is an arithmetic number, because the mean of its divisors is an integer number (1923840).

Almost surely, 2^20520840 is an apocalyptic number.

20520840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20520840 is an abundant number, since it is smaller than the sum of its proper divisors (41042040).

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

20520840 is a wasteful number, since it uses less digits than its factorization.

20520840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 171021 (or 171017 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 21.

The square root of 20520840 is about 4529.9933774786. The cubic root of 20520840 is about 273.7778937820. Note that the first 3 decimals are identical.

The spelling of 20520840 in words is "twenty million, five hundred twenty thousand, eight hundred forty".