1961961857 has 8 divisors (see below), whose sum is σ = 2078846856. Its totient is φ = 1845240832.

The previous prime is 1961961839. The next prime is 1961961863. The reversal of 1961961857 is 7581691691.

It can be written as a sum of positive squares in 4 ways, for example, as 798401536 + 1163560321 = 28256^2 + 34111^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1961961857 - 2⁸ = 1961961601 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1961961799 and 1961961808.

It is not an unprimeable number, because it can be changed into a prime (1961964857) 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, 15908 + ... + 64629.

It is an arithmetic number, because the mean of its divisors is an integer number (259855857).

Almost surely, 2^1961961857 is an apocalyptic number.

1961961857 is a gapful number since it is divisible by the number (17) formed by its first and last digit.

It is an amenable number.

1961961857 is a deficient number, since it is larger than the sum of its proper divisors (116884999).

1961961857 is a wasteful number, since it uses less digits than its factorization.

1961961857 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81987.

The product of its digits is 816480, while the sum is 53.

The square root of 1961961857 is about 44294.0386169516. The cubic root of 1961961857 is about 1251.8823601134.

The spelling of 1961961857 in words is "one billion, nine hundred sixty-one million, nine hundred sixty-one thousand, eight hundred fifty-seven".