39891997 has 4 divisors (see below), whose sum is σ = 39915616. Its totient is φ = 39868380.

The previous prime is 39891991. The next prime is 39892033. The reversal of 39891997 is 79919893.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-39891997 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (39891991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9063 + ... + 12724.

It is an arithmetic number, because the mean of its divisors is an integer number (9978904).

Almost surely, 2^39891997 is an apocalyptic number.

It is an amenable number.

39891997 is a deficient number, since it is larger than the sum of its proper divisors (23619).

39891997 is a wasteful number, since it uses less digits than its factorization.

39891997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23618.

The product of its digits is 1102248, while the sum is 55.

The square root of 39891997 is about 6316.0111621181. The cubic root of 39891997 is about 341.6871076673.

The spelling of 39891997 in words is "thirty-nine million, eight hundred ninety-one thousand, nine hundred ninety-seven".