20523840 has 56 divisors (see below), whose sum is σ = 65166240. Its totient is φ = 5472768.

The previous prime is 20523827. The next prime is 20523859. The reversal of 20523840 is 4832502.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 20523840.

It is a congruent number.

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, 9730 + ... + 11649.

Almost surely, 2^20523840 is an apocalyptic number.

20523840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20523840 is an abundant number, since it is smaller than the sum of its proper divisors (44642400).

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

20523840 is a wasteful number, since it uses less digits than its factorization.

20523840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21399 (or 21389 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 24.

The square root of 20523840 is about 4530.3244916893. The cubic root of 20523840 is about 273.7912345884.

The spelling of 20523840 in words is "twenty million, five hundred twenty-three thousand, eight hundred forty".