391969906 has 8 divisors (see below), whose sum is σ = 591353964. Its totient is φ = 194851920.

The previous prime is 391969889. The next prime is 391969909. The reversal of 391969906 is 609969193.

It can be written as a sum of positive squares in 2 ways, for example, as 391683681 + 286225 = 19791^2 + 535^2 .

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

It is not an unprimeable number, because it can be changed into a prime (391969909) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 566085 + ... + 566776.

Almost surely, 2^391969906 is an apocalyptic number.

391969906 is the 12522-nd centered pentagonal number.

391969906 is a deficient number, since it is larger than the sum of its proper divisors (199384058).

391969906 is a wasteful number, since it uses less digits than its factorization.

391969906 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1133036.

The product of its (nonzero) digits is 708588, while the sum is 52.

The square root of 391969906 is about 19798.2298703697. The cubic root of 391969906 is about 731.8424130991.

The spelling of 391969906 in words is "three hundred ninety-one million, nine hundred sixty-nine thousand, nine hundred six".