618163681 has 4 divisors (see below), whose sum is σ = 639479700. Its totient is φ = 596847664.

The previous prime is 618163633. The next prime is 618163723. The reversal of 618163681 is 186361816.

618163681 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 477029281 + 141134400 = 21841^2 + 11880^2 .

It is a cyclic number.

It is not a de Polignac number, because 618163681 - 2²³ = 609775073 is a prime.

It is a super-2 number, since 2×618163681² = 764252673014939522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (618163621) 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, 10657966 + ... + 10658023.

It is an arithmetic number, because the mean of its divisors is an integer number (159869925).

Almost surely, 2^618163681 is an apocalyptic number.

It is an amenable number.

618163681 is a deficient number, since it is larger than the sum of its proper divisors (21316019).

618163681 is a wasteful number, since it uses less digits than its factorization.

618163681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21316018.

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

The square root of 618163681 is about 24862.8976790719. The cubic root of 618163681 is about 851.8592202943.

The spelling of 618163681 in words is "six hundred eighteen million, one hundred sixty-three thousand, six hundred eighty-one".