1221637246729 has 9 divisors (see below), whose sum is σ = 1265248467093. Its totient is φ = 1179480876672.

The previous prime is 1221637246703. The next prime is 1221637246733. The reversal of 1221637246729 is 9276427361221.

The square root of 1221637246729 is 1105277.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 11751644025 + 1209885602704 = 108405^2 + 1099948^2 .

It is not a de Polignac number, because 1221637246729 - 2⁷ = 1221637246601 is a prime.

It is a super-2 number, since 2×1221637246729² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221637246429) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 32033977 + ... + 32072089.

Almost surely, 2^{1221637246729} is an apocalyptic number.

1221637246729 is the 1105277-th square number.

1221637246729 is the 552639-th centered octagonal number.

It is an amenable number.

1221637246729 is a deficient number, since it is larger than the sum of its proper divisors (43611220364).

1221637246729 is an frugal number, since it uses more digits than its factorization.

1221637246729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76284 (or 38142 counting only the distinct ones).

The product of its digits is 3048192, while the sum is 52.

The spelling of 1221637246729 in words is "one trillion, two hundred twenty-one billion, six hundred thirty-seven million, two hundred forty-six thousand, seven hundred twenty-nine".