1961688645 has 64 divisors (see below), whose sum is σ = 4045271040. Its totient is φ = 883358784.

The previous prime is 1961688643. The next prime is 1961688647. The reversal of 1961688645 is 5468861691.

1961688645 is a `hidden beast` number, since 19 + 616 + 8 + 8 + 6 + 4 + 5 = 666.

It is an interprime number because it is at equal distance from previous prime (1961688643) and next prime (1961688647).

It is not a de Polignac number, because 1961688645 - 2¹ = 1961688643 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1961688591 and 1961688600.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1961688643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 47824 + ... + 78806.

It is an arithmetic number, because the mean of its divisors is an integer number (63207360).

Almost surely, 2^1961688645 is an apocalyptic number.

1961688645 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1961688645 is an abundant number, since it is smaller than the sum of its proper divisors (2083582395).

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

1961688645 is a wasteful number, since it uses less digits than its factorization.

1961688645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31071 (or 31065 counting only the distinct ones).

The product of its digits is 2488320, while the sum is 54.

The square root of 1961688645 is about 44290.9544376727. The cubic root of 1961688645 is about 1251.8242473355.

The spelling of 1961688645 in words is "one billion, nine hundred sixty-one million, six hundred eighty-eight thousand, six hundred forty-five".