391997747 has 8 divisors (see below), whose sum is σ = 415234512. Its totient is φ = 368780800.

The previous prime is 391997737. The next prime is 391997777. The reversal of 391997747 is 747799193.

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 391997747 - 2¹⁰ = 391996723 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 391997692 and 391997701.

It is not an unprimeable number, because it can be changed into a prime (391997707) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 60872 + ... + 67002.

It is an arithmetic number, because the mean of its divisors is an integer number (51904314).

Almost surely, 2^391997747 is an apocalyptic number.

391997747 is a deficient number, since it is larger than the sum of its proper divisors (23236765).

391997747 is a wasteful number, since it uses less digits than its factorization.

391997747 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9909.

The product of its digits is 3000564, while the sum is 56.

The square root of 391997747 is about 19798.9329762995. The cubic root of 391997747 is about 731.8597398904.

The spelling of 391997747 in words is "three hundred ninety-one million, nine hundred ninety-seven thousand, seven hundred forty-seven".