1961639 has 4 divisors (see below), whose sum is σ = 2003424. Its totient is φ = 1919856.

The previous prime is 1961633. The next prime is 1961651. The reversal of 1961639 is 9361691.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9361691 = 593 ⋅15787.

It is not a de Polignac number, because 1961639 - 2⁴ = 1961623 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1961599 and 1961608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1961633) 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, 20822 + ... + 20915.

It is an arithmetic number, because the mean of its divisors is an integer number (500856).

2^1961639 is an apocalyptic number.

1961639 is a deficient number, since it is larger than the sum of its proper divisors (41785).

1961639 is an equidigital number, since it uses as much as digits as its factorization.

1961639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41784.

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

The square root of 1961639 is about 1400.5852348215. The cubic root of 1961639 is about 125.1813687158.

The spelling of 1961639 in words is "one million, nine hundred sixty-one thousand, six hundred thirty-nine".