1221202001 has 4 divisors (see below), whose sum is σ = 1241900400. Its totient is φ = 1200503604.

The previous prime is 1221201979. The next prime is 1221202007. The reversal of 1221202001 is 1002021221.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1002021221 = 19 ⋅52737959.

It is a cyclic number.

It is not a de Polignac number, because 1221202001 - 2⁶ = 1221201937 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221202007) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10349111 + ... + 10349228.

It is an arithmetic number, because the mean of its divisors is an integer number (310475100).

Almost surely, 2^1221202001 is an apocalyptic number.

It is an amenable number.

1221202001 is a deficient number, since it is larger than the sum of its proper divisors (20698399).

1221202001 is an equidigital number, since it uses as much as digits as its factorization.

1221202001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20698398.

The product of its (nonzero) digits is 16, while the sum is 11.

The square root of 1221202001 is about 34945.7007513085. The cubic root of 1221202001 is about 1068.8805367681.

Adding to 1221202001 its reverse (1002021221), we get a palindrome (2223223222).

The spelling of 1221202001 in words is "one billion, two hundred twenty-one million, two hundred two thousand, one".