20509019887 has 2 divisors, whose sum is σ = 20509019888. Its totient is φ = 20509019886.

The previous prime is 20509019857. The next prime is 20509019899. The reversal of 20509019887 is 78891090502.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20509019887 - 2²⁷ = 20374802159 is a prime.

It is a super-2 number, since 2×20509019887² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 20509019887.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20509019837) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10254509943 + 10254509944.

It is an arithmetic number, because the mean of its divisors is an integer number (10254509944).

Almost surely, 2^20509019887 is an apocalyptic number.

20509019887 is a deficient number, since it is larger than the sum of its proper divisors (1).

20509019887 is an equidigital number, since it uses as much as digits as its factorization.

20509019887 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 362880, while the sum is 49.

The spelling of 20509019887 in words is "twenty billion, five hundred nine million, nineteen thousand, eight hundred eighty-seven".