1261401405 has 24 divisors (see below), whose sum is σ = 2218401696. Its totient is φ = 611587680.

The previous prime is 1261401391. The next prime is 1261401433. The reversal of 1261401405 is 5041041621.

It is a happy number.

It is not a de Polignac number, because 1261401405 - 2⁸ = 1261401149 is a prime.

It is a super-2 number, since 2×1261401405² = 3182267009071948050, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 345679 + ... + 349308.

It is an arithmetic number, because the mean of its divisors is an integer number (92433404).

Almost surely, 2^1261401405 is an apocalyptic number.

1261401405 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1261401405 is a deficient number, since it is larger than the sum of its proper divisors (957000291).

1261401405 is a wasteful number, since it uses less digits than its factorization.

1261401405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 695017 (or 695006 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 24.

The square root of 1261401405 is about 35516.2132694351. The cubic root of 1261401405 is about 1080.4825818300.

The spelling of 1261401405 in words is "one billion, two hundred sixty-one million, four hundred one thousand, four hundred five".