1261955538 has 20 divisors (see below), whose sum is σ = 2827715550. Its totient is φ = 420651792.

The previous prime is 1261955537. The next prime is 1261955573. The reversal of 1261955538 is 8355591621.

1261955538 is a `hidden beast` number, since 1 + 2 + 6 + 1 + 95 + 553 + 8 = 666.

It can be written as a sum of positive squares in only one way, i.e., 940219569 + 321735969 = 30663^2 + 17937^2 .

It is a junction number, because it is equal to n+sod(n) for n = 1261955493 and 1261955502.

It is not an unprimeable number, because it can be changed into a prime (1261955537) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 3894763 + ... + 3895086.

Almost surely, 2^1261955538 is an apocalyptic number.

1261955538 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

1261955538 is an abundant number, since it is smaller than the sum of its proper divisors (1565760012).

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

1261955538 is an equidigital number, since it uses as much as digits as its factorization.

1261955538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7789863 (or 7789854 counting only the distinct ones).

The product of its digits is 324000, while the sum is 45.

The square root of 1261955538 is about 35524.0135401393. The cubic root of 1261955538 is about 1080.6407771513.

The spelling of 1261955538 in words is "one billion, two hundred sixty-one million, nine hundred fifty-five thousand, five hundred thirty-eight".