15787997 has 2 divisors, whose sum is σ = 15787998. Its totient is φ = 15787996.

The previous prime is 15787991. The next prime is 15787999. The reversal of 15787997 is 79978751.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 8637721 + 7150276 = 2939^2 + 2674^2 .

It is a cyclic number.

It is not a de Polignac number, because 15787997 - 2⁸ = 15787741 is a prime.

Together with 15787999, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (15787991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7893998 + 7893999.

It is an arithmetic number, because the mean of its divisors is an integer number (7893999).

Almost surely, 2^15787997 is an apocalyptic number.

It is an amenable number.

15787997 is a deficient number, since it is larger than the sum of its proper divisors (1).

15787997 is an equidigital number, since it uses as much as digits as its factorization.

15787997 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1111320, while the sum is 53.

The square root of 15787997 is about 3973.4112548288. The cubic root of 15787997 is about 250.8663118807.

The spelling of 15787997 in words is "fifteen million, seven hundred eighty-seven thousand, nine hundred ninety-seven".