20513720 has 16 divisors (see below), whose sum is σ = 46155960. Its totient is φ = 8205472.

The previous prime is 20513687. The next prime is 20513729. The reversal of 20513720 is 2731502.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 20513692 and 20513701.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20513729) by changing a digit.

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, 256382 + ... + 256461.

Almost surely, 2^20513720 is an apocalyptic number.

20513720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20513720 is an abundant number, since it is smaller than the sum of its proper divisors (25642240).

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

20513720 is a wasteful number, since it uses less digits than its factorization.

20513720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 512854 (or 512850 counting only the distinct ones).

The product of its (nonzero) digits is 420, while the sum is 20.

The square root of 20513720 is about 4529.2074361857. The cubic root of 20513720 is about 273.7462263959.

The spelling of 20513720 in words is "twenty million, five hundred thirteen thousand, seven hundred twenty".