18978901 has 2 divisors, whose sum is σ = 18978902. Its totient is φ = 18978900.

The previous prime is 18978893. The next prime is 18978917. The reversal of 18978901 is 10987981.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15792676 + 3186225 = 3974^2 + 1785^2 .

It is a cyclic number.

It is not a de Polignac number, because 18978901 - 2³ = 18978893 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18978301) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9489450 + 9489451.

It is an arithmetic number, because the mean of its divisors is an integer number (9489451).

Almost surely, 2^18978901 is an apocalyptic number.

It is an amenable number.

18978901 is a deficient number, since it is larger than the sum of its proper divisors (1).

18978901 is an equidigital number, since it uses as much as digits as its factorization.

18978901 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 36288, while the sum is 43.

The square root of 18978901 is about 4356.4780499849. The cubic root of 18978901 is about 266.7413552944.

The spelling of 18978901 in words is "eighteen million, nine hundred seventy-eight thousand, nine hundred one".