391999997 has 8 divisors (see below), whose sum is σ = 402546144. Its totient is φ = 381518928.

The previous prime is 391999987. The next prime is 392000009. The reversal of 391999997 is 799999193.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 391999997 - 2¹⁰ = 391998973 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 (391999967) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3938 + ... + 28275.

It is an arithmetic number, because the mean of its divisors is an integer number (50318268).

Almost surely, 2^391999997 is an apocalyptic number.

It is an amenable number.

391999997 is a deficient number, since it is larger than the sum of its proper divisors (10546147).

391999997 is a wasteful number, since it uses less digits than its factorization.

391999997 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32539.

The product of its digits is 11160261, while the sum is 65.

The square root of 391999997 is about 19798.9897974619. The cubic root of 391999997 is about 731.8611401376.

The spelling of 391999997 in words is "three hundred ninety-one million, nine hundred ninety-nine thousand, nine hundred ninety-seven".