1261644408 has 48 divisors (see below), whose sum is σ = 3418677600. Its totient is φ = 420336000.

The previous prime is 1261644407. The next prime is 1261644431. The reversal of 1261644408 is 8044461621.

It is a happy number.

1261644408 is a `hidden beast` number, since 1 + 2 + 6 + 1 + 644 + 4 + 0 + 8 = 666.

It is a super-2 number, since 2×1261644408² = 3183493224475340928, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1261644407) 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, 213153 + ... + 218991.

It is an arithmetic number, because the mean of its divisors is an integer number (71222450).

Almost surely, 2^1261644408 is an apocalyptic number.

1261644408 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

1261644408 is an abundant number, since it is smaller than the sum of its proper divisors (2157033192).

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

1261644408 is a wasteful number, since it uses less digits than its factorization.

1261644408 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8852 (or 8845 counting only the distinct ones).

The product of its (nonzero) digits is 36864, while the sum is 36.

The square root of 1261644408 is about 35519.6341197372. The cubic root of 1261644408 is about 1080.5519606572.

The spelling of 1261644408 in words is "one billion, two hundred sixty-one million, six hundred forty-four thousand, four hundred eight".