18947917 has 4 divisors (see below), whose sum is σ = 19031616. Its totient is φ = 18864220.

The previous prime is 18947897. The next prime is 18947927. The reversal of 18947917 is 71974981.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18947917 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 (18947927) 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, 41509 + ... + 41962.

It is an arithmetic number, because the mean of its divisors is an integer number (4757904).

Almost surely, 2^18947917 is an apocalyptic number.

It is an amenable number.

18947917 is a deficient number, since it is larger than the sum of its proper divisors (83699).

18947917 is an equidigital number, since it uses as much as digits as its factorization.

18947917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83698.

The product of its digits is 127008, while the sum is 46.

The square root of 18947917 is about 4352.9205138619. The cubic root of 18947917 is about 266.5961200538.

The spelling of 18947917 in words is "eighteen million, nine hundred forty-seven thousand, nine hundred seventeen".