1581042687761 has 16 divisors (see below), whose sum is σ = 1630344611280. Its totient is φ = 1532088483840.

The previous prime is 1581042687727. The next prime is 1581042687767. The reversal of 1581042687761 is 1677862401851.

It can be written as a sum of positive squares in 8 ways, for example, as 391294036225 + 1189748651536 = 625535^2 + 1090756^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1581042687761 is a prime.

It is a Smith number, since the sum of its digits (56) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 1581042687697 and 1581042687706.

It is not an unprimeable number, because it can be changed into a prime (1581042687767) 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, 121528025 + ... + 121541033.

It is an arithmetic number, because the mean of its divisors is an integer number (101896538205).

Almost surely, 2^{1581042687761} is an apocalyptic number.

It is an amenable number.

1581042687761 is a deficient number, since it is larger than the sum of its proper divisors (49301923519).

1581042687761 is a wasteful number, since it uses less digits than its factorization.

1581042687761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26084.

The product of its (nonzero) digits is 4515840, while the sum is 56.

The spelling of 1581042687761 in words is "one trillion, five hundred eighty-one billion, forty-two million, six hundred eighty-seven thousand, seven hundred sixty-one".