1961981964 has 72 divisors (see below), whose sum is σ = 5031586560. Its totient is φ = 644544000.

The previous prime is 1961981963. The next prime is 1961981977. The reversal of 1961981964 is 4691891691.

1961981964 is a `hidden beast` number, since 1 + 9 + 619 + 8 + 19 + 6 + 4 = 666.

It is a super-2 number, since 2×1961981964² = 7698746454122594592, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1961981964.

It is not an unprimeable number, because it can be changed into a prime (1961981963) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 875157 + ... + 877395.

Almost surely, 2^1961981964 is an apocalyptic number.

It is an amenable number.

1961981964 is an abundant number, since it is smaller than the sum of its proper divisors (3069604596).

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

1961981964 is a wasteful number, since it uses less digits than its factorization.

1961981964 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2591 (or 2586 counting only the distinct ones).

The product of its digits is 839808, while the sum is 54.

The square root of 1961981964 is about 44294.2655882226. The cubic root of 1961981964 is about 1251.8866367023.

The spelling of 1961981964 in words is "one billion, nine hundred sixty-one million, nine hundred eighty-one thousand, nine hundred sixty-four".