21534042321 has 32 divisors (see below), whose sum is σ = 34839469440. Its totient is φ = 13037068800.

The previous prime is 21534042317. The next prime is 21534042347. The reversal of 21534042321 is 12324043512.

21534042321 is a `hidden beast` number, since 21 + 5 + 3 + 404 + 232 + 1 = 666.

It is not a de Polignac number, because 21534042321 - 2² = 21534042317 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21534042121) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 245001 + ... + 321081.

It is an arithmetic number, because the mean of its divisors is an integer number (1088733420).

Almost surely, 2^21534042321 is an apocalyptic number.

It is an amenable number.

21534042321 is a deficient number, since it is larger than the sum of its proper divisors (13305427119).

21534042321 is a wasteful number, since it uses less digits than its factorization.

21534042321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 77054 (or 77048 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 27.

Adding to 21534042321 its reverse (12324043512), we get a palindrome (33858085833).

The spelling of 21534042321 in words is "twenty-one billion, five hundred thirty-four million, forty-two thousand, three hundred twenty-one".