1221691638576 has 60 divisors (see below), whose sum is σ = 3261128609976. Its totient is φ = 394094062080.

The previous prime is 1221691638547. The next prime is 1221691638589. The reversal of 1221691638576 is 6758361961221.

It is a super-2 number, since 2×1221691638576² (a number of 25 digits) contains 22 as substring.

It is an unprimeable number.

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 in 11 ways as a sum of consecutive naturals, for example, 13196281 + ... + 13288536.

Almost surely, 2^{1221691638576} is an apocalyptic number.

1221691638576 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

1221691638576 is an abundant number, since it is smaller than the sum of its proper divisors (2039436971400).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1221691638576 is a wasteful number, since it uses less digits than its factorization.

1221691638576 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26484890 (or 26484853 counting only the distinct ones).

The product of its digits is 6531840, while the sum is 57.

The spelling of 1221691638576 in words is "one trillion, two hundred twenty-one billion, six hundred ninety-one million, six hundred thirty-eight thousand, five hundred seventy-six".