79745821 has 4 divisors (see below), whose sum is σ = 79822044. Its totient is φ = 79669600.

The previous prime is 79745791. The next prime is 79745837. The reversal of 79745821 is 12854797.

79745821 = 6314² + 6315².

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12854797 = 1153 ⋅11149.

It can be written as a sum of positive squares in 2 ways, for example, as 39866596 + 39879225 = 6314^2 + 6315^2 .

It is a cyclic number.

It is not a de Polignac number, because 79745821 - 2¹¹ = 79743773 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (79745891) 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, 36520 + ... + 38641.

It is an arithmetic number, because the mean of its divisors is an integer number (19955511).

Almost surely, 2^79745821 is an apocalyptic number.

79745821 is the 6315-th centered square number.

It is an amenable number.

79745821 is a deficient number, since it is larger than the sum of its proper divisors (76223).

79745821 is a wasteful number, since it uses less digits than its factorization.

79745821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76222.

The product of its digits is 141120, while the sum is 43.

The square root of 79745821 is about 8930.0515676003. The cubic root of 79745821 is about 430.4301104685.

The spelling of 79745821 in words is "seventy-nine million, seven hundred forty-five thousand, eight hundred twenty-one".