1281961049781 has 64 divisors (see below), whose sum is σ = 1938775080960. Its totient is φ = 749188440000.

The previous prime is 1281961049749. The next prime is 1281961049807. The reversal of 1281961049781 is 1879401691821.

It is not a de Polignac number, because 1281961049781 - 2⁵ = 1281961049749 is a prime.

It is a super-2 number, since 2×1281961049781² (a number of 25 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (57).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1281961049701) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 156504396 + ... + 156512586.

It is an arithmetic number, because the mean of its divisors is an integer number (30293360640).

Almost surely, 2^{1281961049781} is an apocalyptic number.

It is an amenable number.

1281961049781 is a deficient number, since it is larger than the sum of its proper divisors (656814031179).

1281961049781 is a wasteful number, since it uses less digits than its factorization.

1281961049781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12118.

The product of its (nonzero) digits is 1741824, while the sum is 57.

The spelling of 1281961049781 in words is "one trillion, two hundred eighty-one billion, nine hundred sixty-one million, forty-nine thousand, seven hundred eighty-one".