1221520213 has 4 divisors (see below), whose sum is σ = 1236237408. Its totient is φ = 1206803020.

The previous prime is 1221520211. The next prime is 1221520217. The reversal of 1221520213 is 3120251221.

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 1221520213 - 2¹ = 1221520211 is a prime.

It is a super-2 number, since 2×1221520213² = 2984223261535130738, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221520211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7358473 + ... + 7358638.

It is an arithmetic number, because the mean of its divisors is an integer number (309059352).

Almost surely, 2^1221520213 is an apocalyptic number.

It is an amenable number.

1221520213 is a deficient number, since it is larger than the sum of its proper divisors (14717195).

1221520213 is an equidigital number, since it uses as much as digits as its factorization.

1221520213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14717194.

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

The square root of 1221520213 is about 34950.2534039454. The cubic root of 1221520213 is about 1068.9733690963.

Adding to 1221520213 its reverse (3120251221), we get a palindrome (4341771434).

The spelling of 1221520213 in words is "one billion, two hundred twenty-one million, five hundred twenty thousand, two hundred thirteen".