1221215020691 has 2 divisors, whose sum is σ = 1221215020692. Its totient is φ = 1221215020690.

The previous prime is 1221215020667. The next prime is 1221215020699. The reversal of 1221215020691 is 1960205121221.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1221215020691 - 2²⁶ = 1221147911827 is a prime.

It is a super-2 number, since 2×1221215020691² (a number of 25 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1221215020699) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610607510345 + 610607510346.

It is an arithmetic number, because the mean of its divisors is an integer number (610607510346).

Almost surely, 2^{1221215020691} is an apocalyptic number.

1221215020691 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221215020691 is an equidigital number, since it uses as much as digits as its factorization.

1221215020691 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4320, while the sum is 32.

The spelling of 1221215020691 in words is "one trillion, two hundred twenty-one billion, two hundred fifteen million, twenty thousand, six hundred ninety-one".