38815991 has 2 divisors, whose sum is σ = 38815992. Its totient is φ = 38815990.

The previous prime is 38815969. The next prime is 38816003. The reversal of 38815991 is 19951883.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 38815991 - 2²² = 34621687 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (38815921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 19407995 + 19407996.

It is an arithmetic number, because the mean of its divisors is an integer number (19407996).

Almost surely, 2^38815991 is an apocalyptic number.

38815991 is a deficient number, since it is larger than the sum of its proper divisors (1).

38815991 is an equidigital number, since it uses as much as digits as its factorization.

38815991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 77760, while the sum is 44.

The square root of 38815991 is about 6230.2480688974. The cubic root of 38815991 is about 338.5869584814.

The spelling of 38815991 in words is "thirty-eight million, eight hundred fifteen thousand, nine hundred ninety-one".