19972987 has 2 divisors, whose sum is σ = 19972988. Its totient is φ = 19972986.

The previous prime is 19972963. The next prime is 19973029. The reversal of 19972987 is 78927991.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 19972987 - 2²³ = 11584379 is a prime.

It is not a weakly prime, because it can be changed into another prime (19972957) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9986493 + 9986494.

It is an arithmetic number, because the mean of its divisors is an integer number (9986494).

Almost surely, 2^19972987 is an apocalyptic number.

19972987 is a deficient number, since it is larger than the sum of its proper divisors (1).

19972987 is an equidigital number, since it uses as much as digits as its factorization.

19972987 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 571536, while the sum is 52.

The square root of 19972987 is about 4469.1147893067. The cubic root of 19972987 is about 271.3194989931.

The spelling of 19972987 in words is "nineteen million, nine hundred seventy-two thousand, nine hundred eighty-seven".