20659799987 has 2 divisors, whose sum is σ = 20659799988. Its totient is φ = 20659799986.

The previous prime is 20659799981. The next prime is 20659800017. The reversal of 20659799987 is 78999795602.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20659799987 - 2⁸ = 20659799731 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20659799987.

It is not a weakly prime, because it can be changed into another prime (20659799981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10329899993 + 10329899994.

It is an arithmetic number, because the mean of its divisors is an integer number (10329899994).

Almost surely, 2^20659799987 is an apocalyptic number.

20659799987 is a deficient number, since it is larger than the sum of its proper divisors (1).

20659799987 is an equidigital number, since it uses as much as digits as its factorization.

20659799987 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 154314720, while the sum is 71.

The spelling of 20659799987 in words is "twenty billion, six hundred fifty-nine million, seven hundred ninety-nine thousand, nine hundred eighty-seven".