221616545 has 4 divisors (see below), whose sum is σ = 265939860. Its totient is φ = 177293232.

The previous prime is 221616541. The next prime is 221616547. The reversal of 221616545 is 545616122.

221616545 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.

It can be written as a sum of positive squares in 2 ways, for example, as 137545984 + 84070561 = 11728^2 + 9169^2 .

It is a cyclic number.

It is not a de Polignac number, because 221616545 - 2² = 221616541 is a prime.

It is a super-2 number, since 2×221616545² = 98227786035474050, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (221616541) 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, 22161650 + ... + 22161659.

It is an arithmetic number, because the mean of its divisors is an integer number (66484965).

Almost surely, 2^221616545 is an apocalyptic number.

It is an amenable number.

221616545 is a deficient number, since it is larger than the sum of its proper divisors (44323315).

221616545 is an equidigital number, since it uses as much as digits as its factorization.

221616545 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44323314.

The product of its digits is 14400, while the sum is 32.

The square root of 221616545 is about 14886.7909570868. The cubic root of 221616545 is about 605.1560692914.

The spelling of 221616545 in words is "two hundred twenty-one million, six hundred sixteen thousand, five hundred forty-five".