1261187490816 has 440 divisors, whose sum is σ = 4166610528960. Its totient is φ = 376775884800.

The previous prime is 1261187490811. The next prime is 1261187490841. The reversal of 1261187490816 is 6180947811621.

1261187490816 is a `hidden beast` number, since 1 + 2 + 61 + 1 + 87 + 490 + 8 + 16 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is not an unprimeable number, because it can be changed into a prime (1261187490811) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 64769530 + ... + 64788998.

It is an arithmetic number, because the mean of its divisors is an integer number (9469569384).

Almost surely, 2^{1261187490816} is an apocalyptic number.

1261187490816 is a gapful number since it is divisible by the number (16) 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 1261187490816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2083305264480).

1261187490816 is an abundant number, since it is smaller than the sum of its proper divisors (2905423038144).

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

1261187490816 is a wasteful number, since it uses less digits than its factorization.

1261187490816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19583 (or 19556 counting only the distinct ones).

The product of its (nonzero) digits is 1161216, while the sum is 54.

The spelling of 1261187490816 in words is "one trillion, two hundred sixty-one billion, one hundred eighty-seven million, four hundred ninety thousand, eight hundred sixteen".