18723997 has 2 divisors, whose sum is σ = 18723998. Its totient is φ = 18723996.

The previous prime is 18723983. The next prime is 18724039. The reversal of 18723997 is 79932781.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13461561 + 5262436 = 3669^2 + 2294^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18723997 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18723917) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9361998 + 9361999.

It is an arithmetic number, because the mean of its divisors is an integer number (9361999).

Almost surely, 2^18723997 is an apocalyptic number.

It is an amenable number.

18723997 is a deficient number, since it is larger than the sum of its proper divisors (1).

18723997 is an equidigital number, since it uses as much as digits as its factorization.

18723997 is an evil number, because the sum of its binary digits is even.

The product of its digits is 190512, while the sum is 46.

The square root of 18723997 is about 4327.1234093795. The cubic root of 18723997 is about 265.5417752096.

The spelling of 18723997 in words is "eighteen million, seven hundred twenty-three thousand, nine hundred ninety-seven".