1261161862961 has 16 divisors (see below), whose sum is σ = 1693308236928. Its totient is φ = 907129411200.

The previous prime is 1261161862957. The next prime is 1261161862967. The reversal of 1261161862961 is 1692681611621.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 1261161862961 - 2² = 1261161862957 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1261161862967) 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, 629949980 + ... + 629951981.

It is an arithmetic number, because the mean of its divisors is an integer number (105831764808).

Almost surely, 2^{1261161862961} is an apocalyptic number.

1261161862961 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1261161862961 is a deficient number, since it is larger than the sum of its proper divisors (432146373967).

1261161862961 is a wasteful number, since it uses less digits than its factorization.

1261161862961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1259901992.

The product of its digits is 373248, while the sum is 50.

The spelling of 1261161862961 in words is "one trillion, two hundred sixty-one billion, one hundred sixty-one million, eight hundred sixty-two thousand, nine hundred sixty-one".