1221618131 has 2 divisors, whose sum is σ = 1221618132. Its totient is φ = 1221618130.

The previous prime is 1221618121. The next prime is 1221618143. The reversal of 1221618131 is 1318161221.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1221618131 - 2¹⁰ = 1221617107 is a prime.

It is a super-2 number, since 2×1221618131² = 2984701715975866322, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1221618131.

It is not a weakly prime, because it can be changed into another prime (1221618121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610809065 + 610809066.

It is an arithmetic number, because the mean of its divisors is an integer number (610809066).

Almost surely, 2^1221618131 is an apocalyptic number.

1221618131 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221618131 is an equidigital number, since it uses as much as digits as its factorization.

1221618131 is an evil number, because the sum of its binary digits is even.

The product of its digits is 576, while the sum is 26.

The square root of 1221618131 is about 34951.6541954741. The cubic root of 1221618131 is about 1069.0019315757.

Adding to 1221618131 its reverse (1318161221), we get a palindrome (2539779352).

The spelling of 1221618131 in words is "one billion, two hundred twenty-one million, six hundred eighteen thousand, one hundred thirty-one".