18491969 has 2 divisors, whose sum is σ = 18491970. Its totient is φ = 18491968.

The previous prime is 18491951. The next prime is 18491981. The reversal of 18491969 is 96919481.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18447025 + 44944 = 4295^2 + 212^2 .

It is an emirp because it is prime and its reverse (96919481) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18491969 - 2⁸ = 18491713 is a prime.

It is a super-2 number, since 2×18491969² = 683905834993922, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (18491929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9245984 + 9245985.

It is an arithmetic number, because the mean of its divisors is an integer number (9245985).

Almost surely, 2^18491969 is an apocalyptic number.

It is an amenable number.

18491969 is a deficient number, since it is larger than the sum of its proper divisors (1).

18491969 is an equidigital number, since it uses as much as digits as its factorization.

18491969 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 139968, while the sum is 47.

The square root of 18491969 is about 4300.2289473934. The cubic root of 18491969 is about 264.4403473238.

The spelling of 18491969 in words is "eighteen million, four hundred ninety-one thousand, nine hundred sixty-nine".