1261331780 has 12 divisors (see below), whose sum is σ = 2648796780. Its totient is φ = 504532704.

The previous prime is 1261331723. The next prime is 1261331801. The reversal of 1261331780 is 871331621.

It can be written as a sum of positive squares in 2 ways, for example, as 329495104 + 931836676 = 18152^2 + 30526^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 31533275 + ... + 31533314.

It is an arithmetic number, because the mean of its divisors is an integer number (220733065).

Almost surely, 2^1261331780 is an apocalyptic number.

1261331780 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1261331780 is an abundant number, since it is smaller than the sum of its proper divisors (1387465000).

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

1261331780 is a wasteful number, since it uses less digits than its factorization.

1261331780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63066598 (or 63066596 counting only the distinct ones).

The product of its (nonzero) digits is 6048, while the sum is 32.

The square root of 1261331780 is about 35515.2330697688. The cubic root of 1261331780 is about 1080.4627018289.

The spelling of 1261331780 in words is "one billion, two hundred sixty-one million, three hundred thirty-one thousand, seven hundred eighty".