18972972497 has 4 divisors (see below), whose sum is σ = 18973326516. Its totient is φ = 18972618480.

The previous prime is 18972972493. The next prime is 18972972523. The reversal of 18972972497 is 79427927981.

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 10950366736 + 8022605761 = 104644^2 + 89569^2 .

It is a cyclic number.

It is not a de Polignac number, because 18972972497 - 2² = 18972972493 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18972972493) 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, 78254 + ... + 209927.

It is an arithmetic number, because the mean of its divisors is an integer number (4743331629).

Almost surely, 2^18972972497 is an apocalyptic number.

It is an amenable number.

18972972497 is a deficient number, since it is larger than the sum of its proper divisors (354019).

18972972497 is an equidigital number, since it uses as much as digits as its factorization.

18972972497 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 354018.

The product of its digits is 32006016, while the sum is 65.

The spelling of 18972972497 in words is "eighteen billion, nine hundred seventy-two million, nine hundred seventy-two thousand, four hundred ninety-seven".