3639991 has 2 divisors, whose sum is σ = 3639992. Its totient is φ = 3639990.

The previous prime is 3639983. The next prime is 3639997. The reversal of 3639991 is 1999363.

It is a strong prime.

It is an emirp because it is prime and its reverse (1999363) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 3639991 - 2³ = 3639983 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3639997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1819995 + 1819996.

It is an arithmetic number, because the mean of its divisors is an integer number (1819996).

Almost surely, 2^3639991 is an apocalyptic number.

3639991 is a deficient number, since it is larger than the sum of its proper divisors (1).

3639991 is an equidigital number, since it uses as much as digits as its factorization.

3639991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 39366, while the sum is 40.

The square root of 3639991 is about 1907.8760441916. The cubic root of 3639991 is about 153.8273068387.

The spelling of 3639991 in words is "three million, six hundred thirty-nine thousand, nine hundred ninety-one".