7997989 has 2 divisors, whose sum is σ = 7997990. Its totient is φ = 7997988.

The previous prime is 7997971. The next prime is 7998013. The reversal of 7997989 is 9897997.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 7935489 + 62500 = 2817^2 + 250^2 .

It is a cyclic number.

It is not a de Polignac number, because 7997989 - 2⁹ = 7997477 is a prime.

It is an Ulam number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (7997959) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3998994 + 3998995.

It is an arithmetic number, because the mean of its divisors is an integer number (3998995).

Almost surely, 2^7997989 is an apocalyptic number.

It is an amenable number.

7997989 is a deficient number, since it is larger than the sum of its proper divisors (1).

7997989 is an equidigital number, since it uses as much as digits as its factorization.

7997989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2571912, while the sum is 58.

The square root of 7997989 is about 2828.0716044683. The cubic root of 7997989 is about 199.9832402623.

The spelling of 7997989 in words is "seven million, nine hundred ninety-seven thousand, nine hundred eighty-nine".