18816779551 has 4 divisors (see below), whose sum is σ = 18817588504. Its totient is φ = 18815970600.

The previous prime is 18816779507. The next prime is 18816779587. The reversal of 18816779551 is 15597761881.

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

It is a cyclic number.

It is not a de Polignac number, because 18816779551 - 2¹³ = 18816771359 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 (18816779591) 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, 368520 + ... + 416461.

It is an arithmetic number, because the mean of its divisors is an integer number (4704397126).

Almost surely, 2^18816779551 is an apocalyptic number.

18816779551 is a deficient number, since it is larger than the sum of its proper divisors (808953).

18816779551 is an equidigital number, since it uses as much as digits as its factorization.

18816779551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 808952.

The product of its digits is 4233600, while the sum is 58.

The spelling of 18816779551 in words is "eighteen billion, eight hundred sixteen million, seven hundred seventy-nine thousand, five hundred fifty-one".