221320436 has 18 divisors (see below), whose sum is σ = 408771090. Its totient is φ = 104835312.

The previous prime is 221320427. The next prime is 221320447. The reversal of 221320436 is 634023122.

It can be written as a sum of positive squares in only one way, i.e., 121440400 + 99880036 = 11020^2 + 9994^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 75191 + ... + 78078.

It is an arithmetic number, because the mean of its divisors is an integer number (22709505).

Almost surely, 2^221320436 is an apocalyptic number.

It is an amenable number.

221320436 is a deficient number, since it is larger than the sum of its proper divisors (187450654).

221320436 is a wasteful number, since it uses less digits than its factorization.

221320436 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 153311 (or 153290 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 23.

The square root of 221320436 is about 14876.8422724717. The cubic root of 221320436 is about 604.8864263277.

Adding to 221320436 its reverse (634023122), we get a palindrome (855343558).

The spelling of 221320436 in words is "two hundred twenty-one million, three hundred twenty thousand, four hundred thirty-six".