1231405920 has 72 divisors (see below), whose sum is σ = 4202177616. Its totient is φ = 328374528.

The previous prime is 1231405919. The next prime is 1231405927. The reversal of 1231405920 is 295041321.

1231405920 is a `hidden beast` number, since 1 + 2 + 31 + 40 + 592 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (72).

It is a super-2 number, since 2×1231405920² = 3032721079622092800, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1231405927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 426132 + ... + 429011.

It is an arithmetic number, because the mean of its divisors is an integer number (58363578).

Almost surely, 2^1231405920 is an apocalyptic number.

1231405920 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1231405920 is an abundant number, since it is smaller than the sum of its proper divisors (2970771696).

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

1231405920 is a wasteful number, since it uses less digits than its factorization.

1231405920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 855164 (or 855153 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

The square root of 1231405920 is about 35091.3938167181. The cubic root of 1231405920 is about 1071.8493420860.

The spelling of 1231405920 in words is "one billion, two hundred thirty-one million, four hundred five thousand, nine hundred twenty".