1639961 has 4 divisors (see below), whose sum is σ = 1660800. Its totient is φ = 1619124.

The previous prime is 1639949. The next prime is 1639987. The reversal of 1639961 is 1699361.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1639961 is a prime.

It is a Duffinian number.

It is a plaindrome in base 13.

It is not an unprimeable number, because it can be changed into a prime (1639901) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10301 + ... + 10458.

It is an arithmetic number, because the mean of its divisors is an integer number (415200).

2^1639961 is an apocalyptic number.

It is an amenable number.

1639961 is a deficient number, since it is larger than the sum of its proper divisors (20839).

1639961 is an equidigital number, since it uses as much as digits as its factorization.

1639961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20838.

The product of its digits is 8748, while the sum is 35.

The square root of 1639961 is about 1280.6096204543. The cubic root of 1639961 is about 117.9264360019.

The spelling of 1639961 in words is "one million, six hundred thirty-nine thousand, nine hundred sixty-one".