18792721 has 2 divisors, whose sum is σ = 18792722. Its totient is φ = 18792720.

The previous prime is 18792713. The next prime is 18792733. The reversal of 18792721 is 12729781.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18662400 + 130321 = 4320^2 + 361^2 .

It is a cyclic number.

It is not a de Polignac number, because 18792721 - 2³ = 18792713 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18792821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9396360 + 9396361.

It is an arithmetic number, because the mean of its divisors is an integer number (9396361).

Almost surely, 2^18792721 is an apocalyptic number.

It is an amenable number.

18792721 is a deficient number, since it is larger than the sum of its proper divisors (1).

18792721 is an equidigital number, since it uses as much as digits as its factorization.

18792721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 14112, while the sum is 37.

The square root of 18792721 is about 4335.0572083884. The cubic root of 18792721 is about 265.8662574128.

The spelling of 18792721 in words is "eighteen million, seven hundred ninety-two thousand, seven hundred twenty-one".