18691538089 has 9 divisors (see below), whose sum is σ = 21744331101. Its totient is φ = 16020498060.

The previous prime is 18691538069. The next prime is 18691538111. The reversal of 18691538089 is 98083519681.

The square root of 18691538089 is 136717.

It is a perfect power (a square), and thus also a powerful number.

It is not a de Polignac number, because 18691538089 - 2²¹ = 18689440937 is a prime.

It is a super-2 number, since 2×18691538089² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18691538039) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 947254 + ... + 966784.

It is an arithmetic number, because the mean of its divisors is an integer number (2416036789).

Almost surely, 2^18691538089 is an apocalyptic number.

18691538089 is the 136717-th square number.

18691538089 is the 68359-th centered octagonal number.

It is an amenable number.

18691538089 is a deficient number, since it is larger than the sum of its proper divisors (3052793012).

18691538089 is an frugal number, since it uses more digits than its factorization.

18691538089 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39076 (or 19538 counting only the distinct ones).

The product of its (nonzero) digits is 3732480, while the sum is 58.

The spelling of 18691538089 in words is "eighteen billion, six hundred ninety-one million, five hundred thirty-eight thousand, eighty-nine".