221681953 has 4 divisors (see below), whose sum is σ = 221905300. Its totient is φ = 221458608.

The previous prime is 221681917. The next prime is 221681963. The reversal of 221681953 is 359186122.

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 153586449 + 68095504 = 12393^2 + 8252^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221681953 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221681903) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 110178 + ... + 112171.

It is an arithmetic number, because the mean of its divisors is an integer number (55476325).

Almost surely, 2^221681953 is an apocalyptic number.

It is an amenable number.

221681953 is a deficient number, since it is larger than the sum of its proper divisors (223347).

221681953 is an equidigital number, since it uses as much as digits as its factorization.

221681953 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 223346.

The product of its digits is 25920, while the sum is 37.

The square root of 221681953 is about 14888.9876418781. The cubic root of 221681953 is about 605.2155987739.

The spelling of 221681953 in words is "two hundred twenty-one million, six hundred eighty-one thousand, nine hundred fifty-three".