18316136821 has 4 divisors (see below), whose sum is σ = 19393556652. Its totient is φ = 17238716992.

The previous prime is 18316136771. The next prime is 18316136827. The reversal of 18316136821 is 12863161381.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 14777076721 + 3539060100 = 121561^2 + 59490^2 .

It is not a de Polignac number, because 18316136821 - 2⁷ = 18316136693 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 (18316136827) 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, 538709890 + ... + 538709923.

It is an arithmetic number, because the mean of its divisors is an integer number (4848389163).

Almost surely, 2^18316136821 is an apocalyptic number.

It is an amenable number.

18316136821 is a deficient number, since it is larger than the sum of its proper divisors (1077419831).

18316136821 is a wasteful number, since it uses less digits than its factorization.

18316136821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1077419830.

The product of its digits is 41472, while the sum is 40.

The spelling of 18316136821 in words is "eighteen billion, three hundred sixteen million, one hundred thirty-six thousand, eight hundred twenty-one".