221215666556 has 12 divisors (see below), whose sum is σ = 409899617568. Its totient is φ = 104101490112.

The previous prime is 221215666549. The next prime is 221215666559. The reversal of 221215666556 is 655666512122.

It is a super-2 number, since 2×221215666556² (a number of 23 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 221215666556.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221215666559) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1626585716 + ... + 1626585851.

It is an arithmetic number, because the mean of its divisors is an integer number (34158301464).

Almost surely, 2^221215666556 is an apocalyptic number.

It is an amenable number.

221215666556 is a deficient number, since it is larger than the sum of its proper divisors (188683951012).

221215666556 is a wasteful number, since it uses less digits than its factorization.

221215666556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3253171588 (or 3253171586 counting only the distinct ones).

The product of its digits is 1296000, while the sum is 47.

The spelling of 221215666556 in words is "two hundred twenty-one billion, two hundred fifteen million, six hundred sixty-six thousand, five hundred fifty-six".