391636 has 24 divisors (see below), whose sum is σ = 798336. Its totient is φ = 164640.

The previous prime is 391631. The next prime is 391639. The reversal of 391636 is 636193.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is an Ulam number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (391631) 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, 1890 + ... + 2086.

It is an arithmetic number, because the mean of its divisors is an integer number (33264).

2³⁹¹⁶³⁶ is an apocalyptic number.

It is an amenable number.

391636 is an abundant number, since it is smaller than the sum of its proper divisors (406700).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

391636 is a wasteful number, since it uses less digits than its factorization.

391636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 279 (or 277 counting only the distinct ones).

The product of its digits is 2916, while the sum is 28.

The square root of 391636 is about 625.8082773502. The cubic root of 391636 is about 73.1634543404.

The spelling of 391636 in words is "three hundred ninety-one thousand, six hundred thirty-six".