221656440 has 64 divisors (see below), whose sum is σ = 665949600. Its totient is φ = 59021312.

The previous prime is 221656427. The next prime is 221656459. The reversal of 221656440 is 44656122.

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 = 221656398 and 221656407.

It is a congruent number.

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, 153964 + ... + 155396.

Almost surely, 2^221656440 is an apocalyptic number.

221656440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

221656440 is an abundant number, since it is smaller than the sum of its proper divisors (444293160).

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

221656440 is a wasteful number, since it uses less digits than its factorization.

221656440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2736 (or 2732 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 30.

The square root of 221656440 is about 14888.1308430575. The cubic root of 221656440 is about 605.1923801375.

The spelling of 221656440 in words is "two hundred twenty-one million, six hundred fifty-six thousand, four hundred forty".