661030221 has 8 divisors (see below), whose sum is σ = 895822624. Its totient is φ = 433462320.

The previous prime is 661030219. The next prime is 661030243. The reversal of 661030221 is 122030166.

It is a happy number.

661030221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is not a de Polignac number, because 661030221 - 2¹ = 661030219 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 (661032221) 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, 1805911 + ... + 1806276.

It is an arithmetic number, because the mean of its divisors is an integer number (111977828).

Almost surely, 2^661030221 is an apocalyptic number.

661030221 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

661030221 is a deficient number, since it is larger than the sum of its proper divisors (234792403).

661030221 is a wasteful number, since it uses less digits than its factorization.

661030221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3612251.

The product of its (nonzero) digits is 432, while the sum is 21.

The square root of 661030221 is about 25710.5079879803. The cubic root of 661030221 is about 871.1115492415. Note that the first 3 decimals are identical.

Adding to 661030221 its reverse (122030166), we get a palindrome (783060387).

The spelling of 661030221 in words is "six hundred sixty-one million, thirty thousand, two hundred twenty-one".