20763386681581 has 4 divisors (see below), whose sum is σ = 21479365532700. Its totient is φ = 20047407830464.

The previous prime is 20763386681563. The next prime is 20763386681599. The reversal of 20763386681581 is 18518668336702.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (20763386681563) and next prime (20763386681599).

It can be written as a sum of positive squares in 2 ways, for example, as 12140060779081 + 8623325902500 = 3484259^2 + 2936550^2 .

It is a cyclic number.

It is not a de Polignac number, because 20763386681581 - 2¹¹ = 20763386679533 is a prime.

It is a super-2 number, since 2×20763386681581² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20763386681281) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 357989425516 + ... + 357989425573.

It is an arithmetic number, because the mean of its divisors is an integer number (5369841383175).

Almost surely, 2^{20763386681581} is an apocalyptic number.

It is an amenable number.

20763386681581 is a deficient number, since it is larger than the sum of its proper divisors (715978851119).

20763386681581 is an equidigital number, since it uses as much as digits as its factorization.

20763386681581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 715978851118.

The product of its (nonzero) digits is 69672960, while the sum is 64.

The spelling of 20763386681581 in words is "twenty trillion, seven hundred sixty-three billion, three hundred eighty-six million, six hundred eighty-one thousand, five hundred eighty-one".