79891661 has 2 divisors, whose sum is σ = 79891662. Its totient is φ = 79891660.

The previous prime is 79891633. The next prime is 79891663. The reversal of 79891661 is 16619897.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 49970761 + 29920900 = 7069^2 + 5470^2 .

It is a cyclic number.

It is not a de Polignac number, because 79891661 - 2⁶ = 79891597 is a prime.

Together with 79891663, 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 (79891663) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39945830 + 39945831.

It is an arithmetic number, because the mean of its divisors is an integer number (39945831).

Almost surely, 2^79891661 is an apocalyptic number.

It is an amenable number.

79891661 is a deficient number, since it is larger than the sum of its proper divisors (1).

79891661 is an equidigital number, since it uses as much as digits as its factorization.

79891661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 163296, while the sum is 47.

The square root of 79891661 is about 8938.2135239655. The cubic root of 79891661 is about 430.6923423871.

The spelling of 79891661 in words is "seventy-nine million, eight hundred ninety-one thousand, six hundred sixty-one".