1221612566 has 4 divisors (see below), whose sum is σ = 1832418852. Its totient is φ = 610806282.

The previous prime is 1221612551. The next prime is 1221612599. The reversal of 1221612566 is 6652161221.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 6652161221 = 14033 ⋅474037.

It is a super-2 number, since 2×1221612566² = 2984674522818208712, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 305403140 + ... + 305403143.

It is an arithmetic number, because the mean of its divisors is an integer number (458104713).

Almost surely, 2^1221612566 is an apocalyptic number.

1221612566 is a deficient number, since it is larger than the sum of its proper divisors (610806286).

1221612566 is an equidigital number, since it uses as much as digits as its factorization.

1221612566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 610806285.

The product of its digits is 8640, while the sum is 32.

The square root of 1221612566 is about 34951.5745854175. The cubic root of 1221612566 is about 1069.0003083175. Note that the first 3 decimals are identical.

Adding to 1221612566 its reverse (6652161221), we get a palindrome (7873773787).

The spelling of 1221612566 in words is "one billion, two hundred twenty-one million, six hundred twelve thousand, five hundred sixty-six".