1261636992 has 384 divisors, whose sum is σ = 4688409600. Its totient is φ = 326937600.

The previous prime is 1261636991. The next prime is 1261637017. The reversal of 1261636992 is 2996361621.

1261636992 is a `hidden beast` number, since 1 + 2 + 6 + 1 + 636 + 9 + 9 + 2 = 666.

It is a tau number, because it is divible by the number of its divisors (384).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1261636991) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 2927017 + ... + 2927447.

It is an arithmetic number, because the mean of its divisors is an integer number (12209400).

Almost surely, 2^1261636992 is an apocalyptic number.

1261636992 is a gapful number since it is divisible by the number (12) 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 1261636992, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2344204800).

1261636992 is an abundant number, since it is smaller than the sum of its proper divisors (3426772608).

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

1261636992 is a wasteful number, since it uses less digits than its factorization.

1261636992 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 483 (or 454 counting only the distinct ones).

The product of its digits is 209952, while the sum is 45.

The square root of 1261636992 is about 35519.5297266166. The cubic root of 1261636992 is about 1080.5498434761.

The spelling of 1261636992 in words is "one billion, two hundred sixty-one million, six hundred thirty-six thousand, nine hundred ninety-two".