18997951 has 4 divisors (see below), whose sum is σ = 21711952. Its totient is φ = 16283952.

The previous prime is 18997919. The next prime is 18997969. The reversal of 18997951 is 15979981.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 18997951 - 2⁵ = 18997919 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 18997895 and 18997904.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18997991) 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, 1356990 + ... + 1357003.

It is an arithmetic number, because the mean of its divisors is an integer number (5427988).

Almost surely, 2^18997951 is an apocalyptic number.

18997951 is a deficient number, since it is larger than the sum of its proper divisors (2714001).

18997951 is an equidigital number, since it uses as much as digits as its factorization.

18997951 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2714000.

The product of its digits is 204120, while the sum is 49.

The square root of 18997951 is about 4358.6639007843. The cubic root of 18997951 is about 266.8305723256.

The spelling of 18997951 in words is "eighteen million, nine hundred ninety-seven thousand, nine hundred fifty-one".