1961335891 has 2 divisors, whose sum is σ = 1961335892. Its totient is φ = 1961335890.

The previous prime is 1961335877. The next prime is 1961335903. The reversal of 1961335891 is 1985331691.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1961335891 - 2⁷ = 1961335763 is a prime.

It is not a weakly prime, because it can be changed into another prime (1961335391) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 980667945 + 980667946.

It is an arithmetic number, because the mean of its divisors is an integer number (980667946).

Almost surely, 2^1961335891 is an apocalyptic number.

1961335891 is a deficient number, since it is larger than the sum of its proper divisors (1).

1961335891 is an equidigital number, since it uses as much as digits as its factorization.

1961335891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 174960, while the sum is 46.

The square root of 1961335891 is about 44286.9720233840. The cubic root of 1961335891 is about 1251.7492078225.

The spelling of 1961335891 in words is "one billion, nine hundred sixty-one million, three hundred thirty-five thousand, eight hundred ninety-one".