1231551321 has 64 divisors (see below), whose sum is σ = 2238007296. Its totient is φ = 581644800.

The previous prime is 1231551311. The next prime is 1231551337.

1231551321 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 1231551321 - 2⁵ = 1231551289 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1231551291 and 1231551300.

It is not an unprimeable number, because it can be changed into a prime (1231551311) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 198141 + ... + 204261.

It is an arithmetic number, because the mean of its divisors is an integer number (34968864).

Almost surely, 2^1231551321 is an apocalyptic number.

1231551321 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1231551321 is a deficient number, since it is larger than the sum of its proper divisors (1006455975).

1231551321 is a wasteful number, since it uses less digits than its factorization.

1231551321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6222.

The product of its digits is 900, while the sum is 24.

The square root of 1231551321 is about 35093.4655028539. The cubic root of 1231551321 is about 1071.8915274261.

It can be divided in two parts, 12315 and 51321, that added together give a palindrome (63636).

The spelling of 1231551321 in words is "one billion, two hundred thirty-one million, five hundred fifty-one thousand, three hundred twenty-one".