20819716987 has 2 divisors, whose sum is σ = 20819716988. Its totient is φ = 20819716986.

The previous prime is 20819716843. The next prime is 20819716991. The reversal of 20819716987 is 78961791802.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20819716987 - 2¹¹ = 20819714939 is a prime.

It is not a weakly prime, because it can be changed into another prime (20819716187) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10409858493 + 10409858494.

It is an arithmetic number, because the mean of its divisors is an integer number (10409858494).

Almost surely, 2^20819716987 is an apocalyptic number.

20819716987 is a deficient number, since it is larger than the sum of its proper divisors (1).

20819716987 is an equidigital number, since it uses as much as digits as its factorization.

20819716987 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3048192, while the sum is 58.

The spelling of 20819716987 in words is "twenty billion, eight hundred nineteen million, seven hundred sixteen thousand, nine hundred eighty-seven".