1261555960 has 48 divisors (see below), whose sum is σ = 3301934760. Its totient is φ = 432532800.

The previous prime is 1261555951. The next prime is 1261555969. The reversal of 1261555960 is 695551621.

It is an interprime number because it is at equal distance from previous prime (1261555951) and next prime (1261555969).

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1261555969) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 319866 + ... + 323785.

Almost surely, 2^1261555960 is an apocalyptic number.

1261555960 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1261555960 is an abundant number, since it is smaller than the sum of its proper divisors (2040378800).

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

1261555960 is a wasteful number, since it uses less digits than its factorization.

1261555960 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 643676 (or 643665 counting only the distinct ones).

The product of its (nonzero) digits is 81000, while the sum is 40.

The square root of 1261555960 is about 35518.3890400452. The cubic root of 1261555960 is about 1080.5267092491.

The spelling of 1261555960 in words is "one billion, two hundred sixty-one million, five hundred fifty-five thousand, nine hundred sixty".