813979 has 4 divisors (see below), whose sum is σ = 856840. Its totient is φ = 771120.

The previous prime is 813971. The next prime is 813991. The reversal of 813979 is 979318.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 979318 = 2 ⋅489659.

It is a cyclic number.

It is not a de Polignac number, because 813979 - 2³ = 813971 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (813971) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21402 + ... + 21439.

It is an arithmetic number, because the mean of its divisors is an integer number (214210).

2⁸¹³⁹⁷⁹ is an apocalyptic number.

813979 is a deficient number, since it is larger than the sum of its proper divisors (42861).

813979 is a wasteful number, since it uses less digits than its factorization.

813979 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42860.

The product of its digits is 13608, while the sum is 37.

The square root of 813979 is about 902.2078474498. The cubic root of 813979 is about 93.3693639234.

It can be divided in two parts, 81397 and 9, that added together give a triangular number (81406 = T₄₀₃).

The spelling of 813979 in words is "eight hundred thirteen thousand, nine hundred seventy-nine".