221206129 has 9 divisors (see below), whose sum is σ = 224910777. Its totient is φ = 217562244.

The previous prime is 221206127. The next prime is 221206169. The reversal of 221206129 is 921602122.

The square root of 221206129 is 14873.

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

It is not a de Polignac number, because 221206129 - 2¹ = 221206127 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221206123) 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, 1591342 + ... + 1591480.

Almost surely, 2^221206129 is an apocalyptic number.

221206129 is the 14873-rd square number.

221206129 is the 7437-th centered octagonal number.

It is an amenable number.

221206129 is a deficient number, since it is larger than the sum of its proper divisors (3704648).

221206129 is an frugal number, since it uses more digits than its factorization.

221206129 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 492 (or 246 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 25.

The cubic root of 221206129 is about 604.7822716746.

Multiplying 221206129 by its sum of digits (25), we get a square (5530153225 = 74365²).

The spelling of 221206129 in words is "two hundred twenty-one million, two hundred six thousand, one hundred twenty-nine".