221308813 has 4 divisors (see below), whose sum is σ = 241427808. Its totient is φ = 201189820.

The previous prime is 221308811. The next prime is 221308819. The reversal of 221308813 is 318803122.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 221308813 - 2¹ = 221308811 is a prime.

It is a super-2 number, since 2×221308813² = 97955181422937938, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221308811) 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, 10059481 + ... + 10059502.

It is an arithmetic number, because the mean of its divisors is an integer number (60356952).

Almost surely, 2^221308813 is an apocalyptic number.

It is an amenable number.

221308813 is a deficient number, since it is larger than the sum of its proper divisors (20118995).

221308813 is a wasteful number, since it uses less digits than its factorization.

221308813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20118994.

The product of its (nonzero) digits is 2304, while the sum is 28.

The square root of 221308813 is about 14876.4516266481. The cubic root of 221308813 is about 604.8758372800.

The spelling of 221308813 in words is "two hundred twenty-one million, three hundred eight thousand, eight hundred thirteen".