221355986 has 4 divisors (see below), whose sum is σ = 332033982. Its totient is φ = 110677992.

The previous prime is 221355983. The next prime is 221355991. The reversal of 221355986 is 689553122.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 689553122 = 2 ⋅344776561.

It can be written as a sum of positive squares in only one way, i.e., 173317225 + 48038761 = 13165^2 + 6931^2 .

It is not an unprimeable number, because it can be changed into a prime (221355983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 55338995 + ... + 55338998.

Almost surely, 2^221355986 is an apocalyptic number.

221355986 is a deficient number, since it is larger than the sum of its proper divisors (110677996).

221355986 is a wasteful number, since it uses less digits than its factorization.

221355986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110677995.

The product of its digits is 129600, while the sum is 41.

The square root of 221355986 is about 14878.0370345016. The cubic root of 221355986 is about 604.9188115902.

The spelling of 221355986 in words is "two hundred twenty-one million, three hundred fifty-five thousand, nine hundred eighty-six".