20309720 has 16 divisors (see below), whose sum is σ = 45696960. Its totient is φ = 8123872.

The previous prime is 20309701. The next prime is 20309749. The reversal of 20309720 is 2790302.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 253832 + ... + 253911.

It is an arithmetic number, because the mean of its divisors is an integer number (2856060).

Almost surely, 2^20309720 is an apocalyptic number.

20309720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20309720 is an abundant number, since it is smaller than the sum of its proper divisors (25387240).

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

20309720 is a wasteful number, since it uses less digits than its factorization.

20309720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 507754 (or 507750 counting only the distinct ones).

The product of its (nonzero) digits is 756, while the sum is 23.

The square root of 20309720 is about 4506.6306704677. The cubic root of 20309720 is about 272.8357727216.

The spelling of 20309720 in words is "twenty million, three hundred nine thousand, seven hundred twenty".