961640 has 32 divisors (see below), whose sum is σ = 2241000. Its totient is φ = 370944.

The previous prime is 961637. The next prime is 961643. The reversal of 961640 is 46169.

961640 = T₂₇₁ + T₂₇₂ + ... + T₂₉₄.

961640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (961637) and next prime (961643).

It can be written as a sum of positive squares in 4 ways, for example, as 806404 + 155236 = 898^2 + 394^2 .

It is an Ulam number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 961640.

It is not an unprimeable number, because it can be changed into a prime (961643) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 746 + ... + 1574.

2⁹⁶¹⁶⁴⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 961640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1120500).

961640 is an abundant number, since it is smaller than the sum of its proper divisors (1279360).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

961640 is a wasteful number, since it uses less digits than its factorization.

961640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 869 (or 865 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 26.

The square root of 961640 is about 980.6324489838. The cubic root of 961640 is about 98.7046258457.

The spelling of 961640 in words is "nine hundred sixty-one thousand, six hundred forty".