1231721955 has 12 divisors (see below), whose sum is σ = 2134984800. Its totient is φ = 656918352.

The previous prime is 1231721941. The next prime is 1231721983. The reversal of 1231721955 is 5591271321.

It is not a de Polignac number, because 1231721955 - 2⁹ = 1231721443 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 13685755 + ... + 13685844.

It is an arithmetic number, because the mean of its divisors is an integer number (177915400).

Almost surely, 2^1231721955 is an apocalyptic number.

1231721955 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1231721955 is a deficient number, since it is larger than the sum of its proper divisors (903262845).

1231721955 is a wasteful number, since it uses less digits than its factorization.

1231721955 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27371610 (or 27371607 counting only the distinct ones).

The product of its digits is 18900, while the sum is 36.

The square root of 1231721955 is about 35095.8965550105. The cubic root of 1231721955 is about 1071.9410294077.

The spelling of 1231721955 in words is "one billion, two hundred thirty-one million, seven hundred twenty-one thousand, nine hundred fifty-five".