19513987 has 2 divisors, whose sum is σ = 19513988. Its totient is φ = 19513986.

The previous prime is 19513957. The next prime is 19513999. The reversal of 19513987 is 78931591.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 19513987 - 2¹¹ = 19511939 is a prime.

It is not a weakly prime, because it can be changed into another prime (19513927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9756993 + 9756994.

It is an arithmetic number, because the mean of its divisors is an integer number (9756994).

Almost surely, 2^19513987 is an apocalyptic number.

19513987 is a deficient number, since it is larger than the sum of its proper divisors (1).

19513987 is an equidigital number, since it uses as much as digits as its factorization.

19513987 is an evil number, because the sum of its binary digits is even.

The product of its digits is 68040, while the sum is 43.

The square root of 19513987 is about 4417.4638651606. The cubic root of 19513987 is about 269.2249699201.

The spelling of 19513987 in words is "nineteen million, five hundred thirteen thousand, nine hundred eighty-seven".