1221025213 has 4 divisors (see below), whose sum is σ = 1222724160. Its totient is φ = 1219326268.

The previous prime is 1221025171. The next prime is 1221025217. The reversal of 1221025213 is 3125201221.

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.

It is a cyclic number.

It is not a de Polignac number, because 1221025213 - 2²⁹ = 684154301 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221025217) 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, 848395 + ... + 849832.

It is an arithmetic number, because the mean of its divisors is an integer number (305681040).

Almost surely, 2^1221025213 is an apocalyptic number.

It is an amenable number.

1221025213 is a deficient number, since it is larger than the sum of its proper divisors (1698947).

1221025213 is an equidigital number, since it uses as much as digits as its factorization.

1221025213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1698946.

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 1221025213 is about 34943.1711926665. The cubic root of 1221025213 is about 1068.8289552467.

Adding to 1221025213 its reverse (3125201221), we get a palindrome (4346226434).

The spelling of 1221025213 in words is "one billion, two hundred twenty-one million, twenty-five thousand, two hundred thirteen".