221681292 has 144 divisors (see below), whose sum is σ = 648563328. Its totient is φ = 58544640.

The previous prime is 221681237. The next prime is 221681321. The reversal of 221681292 is 292186122.

221681292 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 669567 + ... + 669897.

It is an arithmetic number, because the mean of its divisors is an integer number (4503912).

Almost surely, 2^221681292 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 221681292, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (324281664).

221681292 is an abundant number, since it is smaller than the sum of its proper divisors (426882036).

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

221681292 is a wasteful number, since it uses less digits than its factorization.

221681292 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 436 (or 427 counting only the distinct ones).

The product of its digits is 6912, while the sum is 33.

The square root of 221681292 is about 14888.9654442476. The cubic root of 221681292 is about 605.2149972396.

The spelling of 221681292 in words is "two hundred twenty-one million, six hundred eighty-one thousand, two hundred ninety-two".