221781678947 has 16 divisors (see below), whose sum is σ = 229442492160. Its totient is φ = 214212750048.

The previous prime is 221781678941. The next prime is 221781678961. The reversal of 221781678947 is 749876187122.

It is a cyclic number.

It is not a de Polignac number, because 221781678947 - 2²⁴ = 221764901731 is a prime.

It is a super-2 number, since 2×221781678947² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 221781678947.

It is not an unprimeable number, because it can be changed into a prime (221781678941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3859178 + ... + 3916224.

It is an arithmetic number, because the mean of its divisors is an integer number (14340155760).

Almost surely, 2^221781678947 is an apocalyptic number.

221781678947 is a deficient number, since it is larger than the sum of its proper divisors (7660813213).

221781678947 is a wasteful number, since it uses less digits than its factorization.

221781678947 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57850.

The product of its digits is 18966528, while the sum is 62.

The spelling of 221781678947 in words is "two hundred twenty-one billion, seven hundred eighty-one million, six hundred seventy-eight thousand, nine hundred forty-seven".