20561701571720 has 32 divisors (see below), whose sum is σ = 48985230216600. Its totient is φ = 7740875885568.

The previous prime is 20561701571713. The next prime is 20561701571759. The reversal of 20561701571720 is 2717510716502.

It can be written as a sum of positive squares in 4 ways, for example, as 20478756419716 + 82945152004 = 4525346^2 + 288002^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15118897535 + ... + 15118898894.

Almost surely, 2^{20561701571720} is an apocalyptic number.

20561701571720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20561701571720 is an abundant number, since it is smaller than the sum of its proper divisors (28423528644880).

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

20561701571720 is a wasteful number, since it uses less digits than its factorization.

20561701571720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30237796457 (or 30237796453 counting only the distinct ones).

The product of its (nonzero) digits is 205800, while the sum is 44.

The spelling of 20561701571720 in words is "twenty trillion, five hundred sixty-one billion, seven hundred one million, five hundred seventy-one thousand, seven hundred twenty".