222157721 has 8 divisors (see below), whose sum is σ = 228307464. Its totient is φ = 216042880.

The previous prime is 222157711. The next prime is 222157769. The reversal of 222157721 is 127751222.

It can be written as a sum of positive squares in 4 ways, for example, as 4182025 + 217975696 = 2045^2 + 14764^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-222157721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (222157711) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4451 + ... + 21543.

It is an arithmetic number, because the mean of its divisors is an integer number (28538433).

Almost surely, 2^222157721 is an apocalyptic number.

It is an amenable number.

222157721 is a deficient number, since it is larger than the sum of its proper divisors (6149743).

222157721 is a wasteful number, since it uses less digits than its factorization.

222157721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17451.

The product of its digits is 3920, while the sum is 29.

The square root of 222157721 is about 14904.9562562256. The cubic root of 222157721 is about 605.6482553569.

The spelling of 222157721 in words is "two hundred twenty-two million, one hundred fifty-seven thousand, seven hundred twenty-one".