3656991 has 12 divisors (see below), whose sum is σ = 5280648. Its totient is φ = 2250144.

The previous prime is 3656981. The next prime is 3656993. The reversal of 3656991 is 1996563.

It is not a de Polignac number, because 3656991 - 2¹⁵ = 3624223 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

3656991 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3656993) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3100 + ... + 4113.

It is an arithmetic number, because the mean of its divisors is an integer number (440054).

Almost surely, 2^3656991 is an apocalyptic number.

3656991 is a deficient number, since it is larger than the sum of its proper divisors (1623657).

3656991 is a wasteful number, since it uses less digits than its factorization.

3656991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7242 (or 7229 counting only the distinct ones).

The product of its digits is 43740, while the sum is 39.

The square root of 3656991 is about 1912.3260705225. The cubic root of 3656991 is about 154.0664103296.

The spelling of 3656991 in words is "three million, six hundred fifty-six thousand, nine hundred ninety-one".