1261855992 has 128 divisors (see below), whose sum is σ = 3491573760. Its totient is φ = 378639360.

The previous prime is 1261855979. The next prime is 1261856009. The reversal of 1261855992 is 2995581621.

1261855992 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

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, 632148 + ... + 634140.

It is an arithmetic number, because the mean of its divisors is an integer number (27277920).

Almost surely, 2^1261855992 is an apocalyptic number.

1261855992 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 1261855992, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1745786880).

1261855992 is an abundant number, since it is smaller than the sum of its proper divisors (2229717768).

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

1261855992 is a wasteful number, since it uses less digits than its factorization.

1261855992 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2093 (or 2089 counting only the distinct ones).

The product of its digits is 388800, while the sum is 48.

The square root of 1261855992 is about 35522.6124039322. The cubic root of 1261855992 is about 1080.6123619148.

The spelling of 1261855992 in words is "one billion, two hundred sixty-one million, eight hundred fifty-five thousand, nine hundred ninety-two".