1231221421 has 2 divisors, whose sum is σ = 1231221422. Its totient is φ = 1231221420.

The previous prime is 1231221401. The next prime is 1231221427. The reversal of 1231221421 is 1241221321.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1230957225 + 264196 = 35085^2 + 514^2 .

It is a cyclic number.

It is not a de Polignac number, because 1231221421 - 2¹³ = 1231213229 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1231221427) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 615610710 + 615610711.

It is an arithmetic number, because the mean of its divisors is an integer number (615610711).

Almost surely, 2^1231221421 is an apocalyptic number.

It is an amenable number.

1231221421 is a deficient number, since it is larger than the sum of its proper divisors (1).

1231221421 is an equidigital number, since it uses as much as digits as its factorization.

1231221421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 192, while the sum is 19.

The square root of 1231221421 is about 35088.7648827940. The cubic root of 1231221421 is about 1071.7958084229.

Adding to 1231221421 its reverse (1241221321), we get a palindrome (2472442742).

It can be divided in two parts, 12312 and 21421, that added together give a palindrome (33733).

The spelling of 1231221421 in words is "one billion, two hundred thirty-one million, two hundred twenty-one thousand, four hundred twenty-one".