21920985447 has 8 divisors (see below), whose sum is σ = 29779452144. Its totient is φ = 14338254528.

The previous prime is 21920985433. The next prime is 21920985469. The reversal of 21920985447 is 74458902912.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21920985447 - 2²⁷ = 21786767719 is a prime.

It is a super-3 number, since 3×21920985447³ (a number of 32 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21920985447.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21920985347) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 68933758 + ... + 68934075.

It is an arithmetic number, because the mean of its divisors is an integer number (3722431518).

Almost surely, 2^21920985447 is an apocalyptic number.

21920985447 is a deficient number, since it is larger than the sum of its proper divisors (7858466697).

21920985447 is a wasteful number, since it uses less digits than its factorization.

21920985447 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 137867889.

The product of its (nonzero) digits is 1451520, while the sum is 51.

The spelling of 21920985447 in words is "twenty-one billion, nine hundred twenty million, nine hundred eighty-five thousand, four hundred forty-seven".