221051766 has 16 divisors (see below), whose sum is σ = 476111664. Its totient is φ = 68015904.

The previous prime is 221051759. The next prime is 221051783. The reversal of 221051766 is 667150122.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1416921 + ... + 1417076.

It is an arithmetic number, because the mean of its divisors is an integer number (29756979).

Almost surely, 2^221051766 is an apocalyptic number.

221051766 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

221051766 is an abundant number, since it is smaller than the sum of its proper divisors (255059898).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

221051766 is a wasteful number, since it uses less digits than its factorization.

221051766 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2834015.

The product of its (nonzero) digits is 5040, while the sum is 30.

The square root of 221051766 is about 14867.8097243676. The cubic root of 221051766 is about 604.6415616952.

It can be divided in two parts, 22105 and 1766, that added together give a triangular number (23871 = T₂₁₈).

The spelling of 221051766 in words is "two hundred twenty-one million, fifty-one thousand, seven hundred sixty-six".