20807999987 has 2 divisors, whose sum is σ = 20807999988. Its totient is φ = 20807999986.

The previous prime is 20807999963. The next prime is 20808000007. The reversal of 20807999987 is 78999970802.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20807999987 - 2⁸ = 20807999731 is a prime.

It is not a weakly prime, because it can be changed into another prime (20807999917) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10403999993 + 10403999994.

It is an arithmetic number, because the mean of its divisors is an integer number (10403999994).

Almost surely, 2^20807999987 is an apocalyptic number.

20807999987 is a deficient number, since it is larger than the sum of its proper divisors (1).

20807999987 is an equidigital number, since it uses as much as digits as its factorization.

20807999987 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 41150592, while the sum is 68.

The spelling of 20807999987 in words is "twenty billion, eight hundred seven million, nine hundred ninety-nine thousand, nine hundred eighty-seven".