20051720 has 32 divisors (see below), whose sum is σ = 48588120. Its totient is φ = 7403520.

The previous prime is 20051711. The next prime is 20051729. The reversal of 20051720 is 2715002.

It is an interprime number because it is at equal distance from previous prime (20051711) and next prime (20051729).

It can be written as a sum of positive squares in 4 ways, for example, as 9721924 + 10329796 = 3118^2 + 3214^2 .

It is not an unprimeable number, because it can be changed into a prime (20051729) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18761 + ... + 19800.

Almost surely, 2^20051720 is an apocalyptic number.

20051720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20051720 is an abundant number, since it is smaller than the sum of its proper divisors (28536400).

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

20051720 is a wasteful number, since it uses less digits than its factorization.

20051720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38585 (or 38581 counting only the distinct ones).

The product of its (nonzero) digits is 140, while the sum is 17.

The square root of 20051720 is about 4477.9146932473. The cubic root of 20051720 is about 271.6755430541.

Adding to 20051720 its reverse (2715002), we get a palindrome (22766722).

The spelling of 20051720 in words is "twenty million, fifty-one thousand, seven hundred twenty".