1221272517 has 4 divisors (see below), whose sum is σ = 1628363360. Its totient is φ = 814181676.

The previous prime is 1221272461. The next prime is 1221272531. The reversal of 1221272517 is 7152721221.

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 not a de Polignac number, because 1221272517 - 2¹⁴ = 1221256133 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 (1221272417) 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, 203545417 + ... + 203545422.

It is an arithmetic number, because the mean of its divisors is an integer number (407090840).

Almost surely, 2^1221272517 is an apocalyptic number.

It is an amenable number.

1221272517 is a deficient number, since it is larger than the sum of its proper divisors (407090843).

1221272517 is an equidigital number, since it uses as much as digits as its factorization.

1221272517 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 407090842.

The product of its digits is 3920, while the sum is 30.

The square root of 1221272517 is about 34946.7096734442. The cubic root of 1221272517 is about 1068.9011098672.

Adding to 1221272517 its reverse (7152721221), we get a palindrome (8373993738).

The spelling of 1221272517 in words is "one billion, two hundred twenty-one million, two hundred seventy-two thousand, five hundred seventeen".