221285640 has 64 divisors (see below), whose sum is σ = 669772800. Its totient is φ = 58483712.

The previous prime is 221285633. The next prime is 221285671. The reversal of 221285640 is 46582122.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 221285598 and 221285607.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5401 + ... + 21719.

It is an arithmetic number, because the mean of its divisors is an integer number (10465200).

Almost surely, 2^221285640 is an apocalyptic number.

221285640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 221285640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (334886400).

221285640 is an abundant number, since it is smaller than the sum of its proper divisors (448487160).

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

221285640 is a wasteful number, since it uses less digits than its factorization.

221285640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16446 (or 16442 counting only the distinct ones).

The product of its (nonzero) digits is 7680, while the sum is 30.

The square root of 221285640 is about 14875.6727578957. The cubic root of 221285640 is about 604.8547245840.

The spelling of 221285640 in words is "two hundred twenty-one million, two hundred eighty-five thousand, six hundred forty".