1961981251 has 2 divisors, whose sum is σ = 1961981252. Its totient is φ = 1961981250.

The previous prime is 1961981171. The next prime is 1961981261. The reversal of 1961981251 is 1521891691.

It is a strong prime.

It is an emirp because it is prime and its reverse (1521891691) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1961981251 - 2⁷ = 1961981123 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1961981198 and 1961981207.

It is not a weakly prime, because it can be changed into another prime (1961981261) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 980990625 + 980990626.

It is an arithmetic number, because the mean of its divisors is an integer number (980990626).

Almost surely, 2^1961981251 is an apocalyptic number.

1961981251 is a deficient number, since it is larger than the sum of its proper divisors (1).

1961981251 is an equidigital number, since it uses as much as digits as its factorization.

1961981251 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 38880, while the sum is 43.

The square root of 1961981251 is about 44294.2575397760. The cubic root of 1961981251 is about 1251.8864850537.

The spelling of 1961981251 in words is "one billion, nine hundred sixty-one million, nine hundred eighty-one thousand, two hundred fifty-one".