221931893 has 4 divisors (see below), whose sum is σ = 227344908. Its totient is φ = 216518880.

The previous prime is 221931881. The next prime is 221931907. The reversal of 221931893 is 398139122.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 398139122 = 2 ⋅199069561.

It can be written as a sum of positive squares in 2 ways, for example, as 76440049 + 145491844 = 8743^2 + 12062^2 .

It is a cyclic number.

It is not a de Polignac number, because 221931893 - 2¹⁴ = 221915509 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221933893) 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, 2706446 + ... + 2706527.

It is an arithmetic number, because the mean of its divisors is an integer number (56836227).

Almost surely, 2^221931893 is an apocalyptic number.

It is an amenable number.

221931893 is a deficient number, since it is larger than the sum of its proper divisors (5413015).

221931893 is an equidigital number, since it uses as much as digits as its factorization.

221931893 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5413014.

The product of its digits is 23328, while the sum is 38.

The square root of 221931893 is about 14897.3787291590. The cubic root of 221931893 is about 605.4429677145.

The spelling of 221931893 in words is "two hundred twenty-one million, nine hundred thirty-one thousand, eight hundred ninety-three".