18939539641 has 9 divisors (see below), whose sum is σ = 20819505189. Its totient is φ = 17216387100.

The previous prime is 18939539599. The next prime is 18939539651. The reversal of 18939539641 is 14693593981.

It is a happy number.

The square root of 18939539641 is 137621.

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

It is not a de Polignac number, because 18939539641 - 2⁷ = 18939539513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18939539651) 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, 1507576 + ... + 1520086.

Almost surely, 2^18939539641 is an apocalyptic number.

18939539641 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

18939539641 is the 137621-st square number.

18939539641 is the 68811-st centered octagonal number.

It is an amenable number.

18939539641 is a deficient number, since it is larger than the sum of its proper divisors (1879965548).

18939539641 is an frugal number, since it uses more digits than its factorization.

18939539641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25044 (or 12522 counting only the distinct ones).

The product of its digits is 6298560, while the sum is 58.

The spelling of 18939539641 in words is "eighteen billion, nine hundred thirty-nine million, five hundred thirty-nine thousand, six hundred forty-one".