1261801871261 has 4 divisors (see below), whose sum is σ = 1261804290432. Its totient is φ = 1261799452092.

The previous prime is 1261801871221. The next prime is 1261801871287. The reversal of 1261801871261 is 1621781081621.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1261801871261 is a prime.

It is a super-2 number, since 2×1261801871261² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1261801871201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 68195 + ... + 1590048.

It is an arithmetic number, because the mean of its divisors is an integer number (315451072608).

Almost surely, 2^{1261801871261} is an apocalyptic number.

It is an amenable number.

1261801871261 is a deficient number, since it is larger than the sum of its proper divisors (2419171).

1261801871261 is an equidigital number, since it uses as much as digits as its factorization.

1261801871261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2419170.

The product of its (nonzero) digits is 64512, while the sum is 44.

The spelling of 1261801871261 in words is "one trillion, two hundred sixty-one billion, eight hundred one million, eight hundred seventy-one thousand, two hundred sixty-one".