1261621872 has 80 divisors (see below), whose sum is σ = 4138663680. Its totient is φ = 360462528.

The previous prime is 1261621861. The next prime is 1261621873. The reversal of 1261621872 is 2781261621.

1261621872 is a `hidden beast` number, since 1 + 26 + 1 + 621 + 8 + 7 + 2 = 666.

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

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1261621873) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 205578 + ... + 211625.

It is an arithmetic number, because the mean of its divisors is an integer number (51733296).

Almost surely, 2^1261621872 is an apocalyptic number.

1261621872 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

1261621872 is an abundant number, since it is smaller than the sum of its proper divisors (2877041808).

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

1261621872 is a wasteful number, since it uses less digits than its factorization.

1261621872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 417227 (or 417215 counting only the distinct ones).

The product of its digits is 16128, while the sum is 36.

The square root of 1261621872 is about 35519.3168853231. The cubic root of 1261621872 is about 1080.5455268676.

The spelling of 1261621872 in words is "one billion, two hundred sixty-one million, six hundred twenty-one thousand, eight hundred seventy-two".