20391520 has 24 divisors (see below), whose sum is σ = 48175344. Its totient is φ = 8156544.

The previous prime is 20391487. The next prime is 20391557. The reversal of 20391520 is 2519302.

It is a junction number, because it is equal to n+sod(n) for n = 20391491 and 20391500.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 63564 + ... + 63883.

It is an arithmetic number, because the mean of its divisors is an integer number (2007306).

Almost surely, 2^20391520 is an apocalyptic number.

20391520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20391520 is an abundant number, since it is smaller than the sum of its proper divisors (27783824).

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

20391520 is a wasteful number, since it uses less digits than its factorization.

20391520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 127462 (or 127454 counting only the distinct ones).

The product of its (nonzero) digits is 540, while the sum is 22.

The square root of 20391520 is about 4515.6970668990. The cubic root of 20391520 is about 273.2015757337.

The spelling of 20391520 in words is "twenty million, three hundred ninety-one thousand, five hundred twenty".