39991693 has 6 divisors (see below), whose sum is σ = 46521006. Its totient is φ = 34278552.

The previous prime is 39991681. The next prime is 39991727. The reversal of 39991693 is 39619993.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 39778249 + 213444 = 6307^2 + 462^2 .

It is not a de Polignac number, because 39991693 - 2¹⁷ = 39860621 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (49), and also a Moran number because the ratio is a prime number: 816157 = 39991693 / (3 + 9 + 9 + 9 + 1 + 6 + 9 + 3).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (39991603) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 408030 + ... + 408127.

It is an arithmetic number, because the mean of its divisors is an integer number (7753501).

Almost surely, 2^39991693 is an apocalyptic number.

It is an amenable number.

39991693 is a deficient number, since it is larger than the sum of its proper divisors (6529313).

39991693 is an equidigital number, since it uses as much as digits as its factorization.

39991693 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 816171 (or 816164 counting only the distinct ones).

The product of its digits is 354294, while the sum is 49.

The square root of 39991693 is about 6323.8985602237. The cubic root of 39991693 is about 341.9715130793.

The spelling of 39991693 in words is "thirty-nine million, nine hundred ninety-one thousand, six hundred ninety-three".