727121221 has 4 divisors (see below), whose sum is σ = 727258444. Its totient is φ = 726984000.

The previous prime is 727121209. The next prime is 727121231. The reversal of 727121221 is 122121727.

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 256448196 + 470673025 = 16014^2 + 21695^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-727121221 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (727121201) 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, 60330 + ... + 71371.

It is an arithmetic number, because the mean of its divisors is an integer number (181814611).

Almost surely, 2^727121221 is an apocalyptic number.

It is an amenable number.

727121221 is a deficient number, since it is larger than the sum of its proper divisors (137223).

727121221 is a wasteful number, since it uses less digits than its factorization.

727121221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 137222.

The product of its digits is 784, while the sum is 25.

The square root of 727121221 is about 26965.1853507444. The cubic root of 727121221 is about 899.2261747690.

Adding to 727121221 its reverse (122121727), we get a palindrome (849242948).

The spelling of 727121221 in words is "seven hundred twenty-seven million, one hundred twenty-one thousand, two hundred twenty-one".