1231237921 has 3 divisors (see below), whose sum is σ = 1231273011. Its totient is φ = 1231202832.

The previous prime is 1231237907. The next prime is 1231237927. The reversal of 1231237921 is 1297321321.

The square root of 1231237921 is 35089.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 1016908321 + 214329600 = 31889^2 + 14640^2 .

It is not a de Polignac number, because 1231237921 - 2⁹ = 1231237409 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1231237927) 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 2 ways as a sum of consecutive naturals, for example, 17545 + ... + 52633.

It is an arithmetic number, because the mean of its divisors is an integer number (410424337).

Almost surely, 2^1231237921 is an apocalyptic number.

1231237921 is the 35089-th square number.

1231237921 is the 17545-th centered octagonal number.

It is an amenable number.

1231237921 is a deficient number, since it is larger than the sum of its proper divisors (35090).

1231237921 is an frugal number, since it uses more digits than its factorization.

1231237921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 70178 (or 35089 counting only the distinct ones).

The product of its digits is 4536, while the sum is 31.

The cubic root of 1231237921 is about 1071.8005962300.

It can be divided in two parts, 123123 and 7921, that added together give a square (131044 = 362²).

The spelling of 1231237921 in words is "one billion, two hundred thirty-one million, two hundred thirty-seven thousand, nine hundred twenty-one".