21354221673 has 8 divisors (see below), whose sum is σ = 31635884000. Its totient is φ = 14236147764.

The previous prime is 21354221671. The next prime is 21354221677. The reversal of 21354221673 is 37612245312.

21354221673 is a `hidden beast` number, since 21 + 3 + 542 + 21 + 6 + 73 = 666.

It is not a de Polignac number, because 21354221673 - 2¹ = 21354221671 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21354221671) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 395448523 + ... + 395448576.

It is an arithmetic number, because the mean of its divisors is an integer number (3954485500).

Almost surely, 2^21354221673 is an apocalyptic number.

It is an amenable number.

21354221673 is a deficient number, since it is larger than the sum of its proper divisors (10281662327).

21354221673 is an equidigital number, since it uses as much as digits as its factorization.

21354221673 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 790897108 (or 790897102 counting only the distinct ones).

The product of its digits is 60480, while the sum is 36.

Adding to 21354221673 its reverse (37612245312), we get a palindrome (58966466985).

The spelling of 21354221673 in words is "twenty-one billion, three hundred fifty-four million, two hundred twenty-one thousand, six hundred seventy-three".