20751390681 has 12 divisors (see below), whose sum is σ = 32185830672. Its totient is φ = 11857937448.

The previous prime is 20751390661. The next prime is 20751390743. The reversal of 20751390681 is 18609315702.

It is not a de Polignac number, because 20751390681 - 2⁹ = 20751390169 is a prime.

It is a super-2 number, since 2×20751390681² (a number of 21 digits) contains 22 as substring.

It is a hoax number, since the sum of its digits (42) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (20751390601) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 70582815 + ... + 70583108.

It is an arithmetic number, because the mean of its divisors is an integer number (2682152556).

Almost surely, 2^20751390681 is an apocalyptic number.

20751390681 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

20751390681 is a deficient number, since it is larger than the sum of its proper divisors (11434439991).

20751390681 is a wasteful number, since it uses less digits than its factorization.

20751390681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 141165940 (or 141165933 counting only the distinct ones).

The product of its (nonzero) digits is 90720, while the sum is 42.

The spelling of 20751390681 in words is "twenty billion, seven hundred fifty-one million, three hundred ninety thousand, six hundred eighty-one".