3639921 has 16 divisors (see below), whose sum is σ = 5184000. Its totient is φ = 2263808.

The previous prime is 3639919. The next prime is 3639929. The reversal of 3639921 is 1299363.

It is a cyclic number.

It is not a de Polignac number, because 3639921 - 2¹ = 3639919 is a prime.

3639921 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (3639929) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7360 + ... + 7838.

It is an arithmetic number, because the mean of its divisors is an integer number (324000).

Almost surely, 2^3639921 is an apocalyptic number.

It is an amenable number.

3639921 is a deficient number, since it is larger than the sum of its proper divisors (1544079).

3639921 is a wasteful number, since it uses less digits than its factorization.

3639921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 648.

The product of its digits is 8748, while the sum is 33.

The square root of 3639921 is about 1907.8576990960. The cubic root of 3639921 is about 153.8263207574.

It can be divided in two parts, 3639 and 921, that added together give a triangular number (4560 = T₉₅).

The spelling of 3639921 in words is "three million, six hundred thirty-nine thousand, nine hundred twenty-one".