1221564413 has 4 divisors (see below), whose sum is σ = 1221641148. Its totient is φ = 1221487680.

The previous prime is 1221564401. The next prime is 1221564457. The reversal of 1221564413 is 3144651221.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 1001279449 + 220284964 = 31643^2 + 14842^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221564413 - 2¹² = 1221560317 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 (1221564713) 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, 4556 + ... + 49637.

It is an arithmetic number, because the mean of its divisors is an integer number (305410287).

Almost surely, 2^1221564413 is an apocalyptic number.

It is an amenable number.

1221564413 is a deficient number, since it is larger than the sum of its proper divisors (76735).

1221564413 is an equidigital number, since it uses as much as digits as its factorization.

1221564413 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76734.

The product of its digits is 5760, while the sum is 29.

The square root of 1221564413 is about 34950.8857255435. The cubic root of 1221564413 is about 1068.9862623345.

The spelling of 1221564413 in words is "one billion, two hundred twenty-one million, five hundred sixty-four thousand, four hundred thirteen".