20987207077 has 2 divisors, whose sum is σ = 20987207078. Its totient is φ = 20987207076.

The previous prime is 20987207053. The next prime is 20987207191. The reversal of 20987207077 is 77070278902.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17954392036 + 3032815041 = 133994^2 + 55071^2 .

It is a cyclic number.

It is not a de Polignac number, because 20987207077 - 2¹⁵ = 20987174309 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20987207077.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20987207677) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10493603538 + 10493603539.

It is an arithmetic number, because the mean of its divisors is an integer number (10493603539).

Almost surely, 2^20987207077 is an apocalyptic number.

It is an amenable number.

20987207077 is a deficient number, since it is larger than the sum of its proper divisors (1).

20987207077 is an equidigital number, since it uses as much as digits as its factorization.

20987207077 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 691488, while the sum is 49.

The spelling of 20987207077 in words is "twenty billion, nine hundred eighty-seven million, two hundred seven thousand, seventy-seven".