20686772137 has 2 divisors, whose sum is σ = 20686772138. Its totient is φ = 20686772136.

The previous prime is 20686772123. The next prime is 20686772143. The reversal of 20686772137 is 73127768602.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11136791961 + 9549980176 = 105531^2 + 97724^2 .

It is a cyclic number.

It is not a de Polignac number, because 20686772137 - 2¹⁵ = 20686739369 is a prime.

It is not a weakly prime, because it can be changed into another prime (20686772837) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10343386068 + 10343386069.

It is an arithmetic number, because the mean of its divisors is an integer number (10343386069).

Almost surely, 2^20686772137 is an apocalyptic number.

It is an amenable number.

20686772137 is a deficient number, since it is larger than the sum of its proper divisors (1).

20686772137 is an equidigital number, since it uses as much as digits as its factorization.

20686772137 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1185408, while the sum is 49.

The spelling of 20686772137 in words is "twenty billion, six hundred eighty-six million, seven hundred seventy-two thousand, one hundred thirty-seven".