221781587328 has 640 divisors, whose sum is σ = 784056651840. Its totient is φ = 60914073600.

The previous prime is 221781587267. The next prime is 221781587341. The reversal of 221781587328 is 823785187122.

It is a happy number.

221781587328 is a `hidden beast` number, since 2 + 21 + 7 + 8 + 1 + 587 + 32 + 8 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 217219458 + ... + 217220478.

Almost surely, 2^221781587328 is an apocalyptic number.

221781587328 is a gapful number since it is divisible by the number (28) 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 221781587328, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (392028325920).

221781587328 is an abundant number, since it is smaller than the sum of its proper divisors (562275064512).

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

221781587328 is a wasteful number, since it uses less digits than its factorization.

221781587328 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1168 (or 1147 counting only the distinct ones).

The product of its digits is 3010560, while the sum is 54.

The spelling of 221781587328 in words is "two hundred twenty-one billion, seven hundred eighty-one million, five hundred eighty-seven thousand, three hundred twenty-eight".