19657997 has 2 divisors, whose sum is σ = 19657998. Its totient is φ = 19657996.

The previous prime is 19657943. The next prime is 19658003. The reversal of 19657997 is 79975691.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11195716 + 8462281 = 3346^2 + 2909^2 .

It is a cyclic number.

It is not a de Polignac number, because 19657997 - 2⁸ = 19657741 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19657927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9828998 + 9828999.

It is an arithmetic number, because the mean of its divisors is an integer number (9828999).

Almost surely, 2^19657997 is an apocalyptic number.

It is an amenable number.

19657997 is a deficient number, since it is larger than the sum of its proper divisors (1).

19657997 is an equidigital number, since it uses as much as digits as its factorization.

19657997 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1071630, while the sum is 53.

The square root of 19657997 is about 4433.7339793903. The cubic root of 19657997 is about 269.8856259970.

The spelling of 19657997 in words is "nineteen million, six hundred fifty-seven thousand, nine hundred ninety-seven".