221771664 has 135 divisors (see below), whose sum is σ = 668464563. Its totient is φ = 68622336.

The previous prime is 221771657. The next prime is 221771687. The reversal of 221771664 is 466177122.

The square root of 221771664 is 14892.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 28005264 + 193766400 = 5292^2 + 13920^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 3037932 + ... + 3038004.

Almost surely, 2^221771664 is an apocalyptic number.

221771664 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

221771664 is the 14892-nd square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 221771664

221771664 is an abundant number, since it is smaller than the sum of its proper divisors (446692899).

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

221771664 is a wasteful number, since it uses less digits than its factorization.

221771664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 194 (or 95 counting only the distinct ones).

The product of its digits is 28224, while the sum is 36.

The cubic root of 221771664 is about 605.2972279931.

Multiplying 221771664 by its sum of digits (36), we get a square (7983779904 = 89352²).

221771664 divided by its sum of digits (36) gives a square (6160324 = 2482²).

Multiplying 221771664 by its product of digits (28224), we get a square (6259283444736 = 2501856²).

The spelling of 221771664 in words is "two hundred twenty-one million, seven hundred seventy-one thousand, six hundred sixty-four".