1213220551 has 4 divisors (see below), whose sum is σ = 1213404192. Its totient is φ = 1213036912.

The previous prime is 1213220549. The next prime is 1213220563. The reversal of 1213220551 is 1550223121.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1550223121 = 83 ⋅18677387.

It is a cyclic number.

It is not a de Polignac number, because 1213220551 - 2¹ = 1213220549 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 (1213220501) 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, 81526 + ... + 95251.

It is an arithmetic number, because the mean of its divisors is an integer number (303351048).

Almost surely, 2^1213220551 is an apocalyptic number.

1213220551 is a deficient number, since it is larger than the sum of its proper divisors (183641).

1213220551 is an equidigital number, since it uses as much as digits as its factorization.

1213220551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 183640.

The product of its (nonzero) digits is 600, while the sum is 22.

The square root of 1213220551 is about 34831.3156656478. The cubic root of 1213220551 is about 1066.5468059437.

Adding to 1213220551 its reverse (1550223121), we get a palindrome (2763443672).

The spelling of 1213220551 in words is "one billion, two hundred thirteen million, two hundred twenty thousand, five hundred fifty-one".