1221452561 has 4 divisors (see below), whose sum is σ = 1395945792. Its totient is φ = 1046959332.

The previous prime is 1221452549. The next prime is 1221452581. The reversal of 1221452561 is 1652541221.

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: 1652541221 = 743 ⋅2224147.

It is a cyclic number.

It is not a de Polignac number, because 1221452561 - 2²² = 1217258257 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221452581) 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, 87246605 + ... + 87246618.

It is an arithmetic number, because the mean of its divisors is an integer number (348986448).

Almost surely, 2^1221452561 is an apocalyptic number.

It is an amenable number.

1221452561 is a deficient number, since it is larger than the sum of its proper divisors (174493231).

1221452561 is an equidigital number, since it uses as much as digits as its factorization.

1221452561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 174493230.

The product of its digits is 4800, while the sum is 29.

The square root of 1221452561 is about 34949.2855577907. The cubic root of 1221452561 is about 1068.9536342553.

Adding to 1221452561 its reverse (1652541221), we get a palindrome (2873993782).

The spelling of 1221452561 in words is "one billion, two hundred twenty-one million, four hundred fifty-two thousand, five hundred sixty-one".