1639897997 has 2 divisors, whose sum is σ = 1639897998. Its totient is φ = 1639897996.

The previous prime is 1639897957. The next prime is 1639898011. The reversal of 1639897997 is 7997989361.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1391961481 + 247936516 = 37309^2 + 15746^2 .

It is a cyclic number.

It is not a de Polignac number, because 1639897997 - 2⁶ = 1639897933 is a prime.

It is a super-2 number, since 2×1639897997² = 5378530881129224018, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1639897927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 819948998 + 819948999.

It is an arithmetic number, because the mean of its divisors is an integer number (819948999).

Almost surely, 2^1639897997 is an apocalyptic number.

It is an amenable number.

1639897997 is a deficient number, since it is larger than the sum of its proper divisors (1).

1639897997 is an equidigital number, since it uses as much as digits as its factorization.

1639897997 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 46294416, while the sum is 68.

The square root of 1639897997 is about 40495.6540507744. The cubic root of 1639897997 is about 1179.2492584107.

The spelling of 1639897997 in words is "one billion, six hundred thirty-nine million, eight hundred ninety-seven thousand, nine hundred ninety-seven".