221613729 has 4 divisors (see below), whose sum is σ = 295484976. Its totient is φ = 147742484.

The previous prime is 221613727. The next prime is 221613731. The reversal of 221613729 is 927316122.

221613729 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (221613727) and next prime (221613731).

It is a cyclic number.

It is not a de Polignac number, because 221613729 - 2¹ = 221613727 is a prime.

It is a super-2 number, since 2×221613729² = 98225289762570882, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 221613729.

It is not an unprimeable number, because it can be changed into a prime (221613727) 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, 36935619 + ... + 36935624.

It is an arithmetic number, because the mean of its divisors is an integer number (73871244).

Almost surely, 2^221613729 is an apocalyptic number.

It is an amenable number.

221613729 is a deficient number, since it is larger than the sum of its proper divisors (73871247).

221613729 is an equidigital number, since it uses as much as digits as its factorization.

221613729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73871246.

The product of its digits is 9072, while the sum is 33.

The square root of 221613729 is about 14886.6963762952. The cubic root of 221613729 is about 605.1535061152.

The spelling of 221613729 in words is "two hundred twenty-one million, six hundred thirteen thousand, seven hundred twenty-nine".