4001639 has 2 divisors, whose sum is σ = 4001640. Its totient is φ = 4001638.

The previous prime is 4001629. The next prime is 4001689. The reversal of 4001639 is 9361004.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 4001639 - 2⁸ = 4001383 is a prime.

It is a super-2 number, since 2×4001639² = 32026229372642, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (4001629) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2000819 + 2000820.

It is an arithmetic number, because the mean of its divisors is an integer number (2000820).

Almost surely, 2^4001639 is an apocalyptic number.

4001639 is a deficient number, since it is larger than the sum of its proper divisors (1).

4001639 is an equidigital number, since it uses as much as digits as its factorization.

4001639 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 648, while the sum is 23.

The square root of 4001639 is about 2000.4097080348. The cubic root of 4001639 is about 158.7617834889.

The spelling of 4001639 in words is "four million, one thousand, six hundred thirty-nine".