20431720 has 16 divisors (see below), whose sum is σ = 45971460. Its totient is φ = 8172672.

The previous prime is 20431687. The next prime is 20431721. The reversal of 20431720 is 2713402.

It can be written as a sum of positive squares in 2 ways, for example, as 20088324 + 343396 = 4482^2 + 586^2 .

It is not an unprimeable number, because it can be changed into a prime (20431721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 255357 + ... + 255436.

Almost surely, 2^20431720 is an apocalyptic number.

20431720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20431720 is an abundant number, since it is smaller than the sum of its proper divisors (25539740).

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

20431720 is a wasteful number, since it uses less digits than its factorization.

20431720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 510804 (or 510800 counting only the distinct ones).

The product of its (nonzero) digits is 336, while the sum is 19.

The square root of 20431720 is about 4520.1460153407. The cubic root of 20431720 is about 273.3809884521.

The spelling of 20431720 in words is "twenty million, four hundred thirty-one thousand, seven hundred twenty".