1221231001 has 2 divisors, whose sum is σ = 1221231002. Its totient is φ = 1221231000.

The previous prime is 1221230993. The next prime is 1221231013. The reversal of 1221231001 is 1001321221.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1083989776 + 137241225 = 32924^2 + 11715^2 .

It is an emirp because it is prime and its reverse (1001321221) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1221231001 - 2³ = 1221230993 is a prime.

It is not a weakly prime, because it can be changed into another prime (1221231031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610615500 + 610615501.

It is an arithmetic number, because the mean of its divisors is an integer number (610615501).

Almost surely, 2^1221231001 is an apocalyptic number.

It is an amenable number.

1221231001 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221231001 is an equidigital number, since it uses as much as digits as its factorization.

1221231001 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 24, while the sum is 13.

The square root of 1221231001 is about 34946.1156782839. The cubic root of 1221231001 is about 1068.8889976371. Note that the first 3 decimals are identical.

Adding to 1221231001 its reverse (1001321221), we get a palindrome (2222552222).

The spelling of 1221231001 in words is "one billion, two hundred twenty-one million, two hundred thirty-one thousand, one".