221640965 has 72 divisors (see below), whose sum is σ = 344723688. Its totient is φ = 136281600.

The previous prime is 221640943. The next prime is 221640973. The reversal of 221640965 is 569046122.

It is a happy number.

It can be written as a sum of positive squares in 12 ways, for example, as 41383489 + 180257476 = 6433^2 + 13426^2 .

It is not a de Polignac number, because 221640965 - 2¹² = 221636869 is a prime.

It is a super-2 number, since 2×221640965² = 98249434732262450, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 2194415 + ... + 2194515.

It is an arithmetic number, because the mean of its divisors is an integer number (4787829).

Almost surely, 2^221640965 is an apocalyptic number.

It is an amenable number.

221640965 is a deficient number, since it is larger than the sum of its proper divisors (123082723).

221640965 is a wasteful number, since it uses less digits than its factorization.

221640965 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 199 (or 179 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 35.

The square root of 221640965 is about 14887.6111246902. The cubic root of 221640965 is about 605.1782959238.

The spelling of 221640965 in words is "two hundred twenty-one million, six hundred forty thousand, nine hundred sixty-five".