1261637912728 has 32 divisors (see below), whose sum is σ = 2423437072560. Its totient is φ = 615390174720.

The previous prime is 1261637912681. The next prime is 1261637912729. The reversal of 1261637912728 is 8272197361621.

It is a Smith number, since the sum of its digits (55) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1261637912729) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4854700 + ... + 5107972.

Almost surely, 2^{1261637912728} is an apocalyptic number.

It is an amenable number.

1261637912728 is a deficient number, since it is larger than the sum of its proper divisors (1161799159832).

1261637912728 is a wasteful number, since it uses less digits than its factorization.

1261637912728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 268507 (or 268503 counting only the distinct ones).

The product of its digits is 3048192, while the sum is 55.

The spelling of 1261637912728 in words is "one trillion, two hundred sixty-one billion, six hundred thirty-seven million, nine hundred twelve thousand, seven hundred twenty-eight".