1261156777320 has 128 divisors (see below), whose sum is σ = 4131399168000. Its totient is φ = 305440385280.

The previous prime is 1261156777273. The next prime is 1261156777333. The reversal of 1261156777320 is 237776511621.

It is a self number, because there is not a number n which added to its sum of digits gives 1261156777320.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 911701 + ... + 1831259.

It is an arithmetic number, because the mean of its divisors is an integer number (32276556000).

Almost surely, 2^{1261156777320} is an apocalyptic number.

1261156777320 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1261156777320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2065699584000).

1261156777320 is an abundant number, since it is smaller than the sum of its proper divisors (2870242390680).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1261156777320 is a wasteful number, since it uses less digits than its factorization.

1261156777320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 920623 (or 920619 counting only the distinct ones).

The product of its (nonzero) digits is 740880, while the sum is 48.

The spelling of 1261156777320 in words is "one trillion, two hundred sixty-one billion, one hundred fifty-six million, seven hundred seventy-seven thousand, three hundred twenty".