1961322781 has 16 divisors (see below), whose sum is σ = 2228990400. Its totient is φ = 1710025600.

The previous prime is 1961322773. The next prime is 1961322817. The reversal of 1961322781 is 1872231691.

It is a cyclic number.

It is not a de Polignac number, because 1961322781 - 2³ = 1961322773 is a prime.

It is a super-2 number, since 2×1961322781² = 7693574102539147922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1961322731) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10246 + ... + 63463.

It is an arithmetic number, because the mean of its divisors is an integer number (139311900).

Almost surely, 2^1961322781 is an apocalyptic number.

1961322781 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1961322781 is a deficient number, since it is larger than the sum of its proper divisors (267667619).

1961322781 is a wasteful number, since it uses less digits than its factorization.

1961322781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73820.

The product of its digits is 36288, while the sum is 40.

The square root of 1961322781 is about 44286.8240112113. The cubic root of 1961322781 is about 1251.7464188274.

The spelling of 1961322781 in words is "one billion, nine hundred sixty-one million, three hundred twenty-two thousand, seven hundred eighty-one".