21533342721 has 24 divisors (see below), whose sum is σ = 32103873312. Its totient is φ = 12732172800.

The previous prime is 21533342687. The next prime is 21533342773. The reversal of 21533342721 is 12724333512.

It is not a de Polignac number, because 21533342721 - 2⁶ = 21533342657 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is not an unprimeable number, because it can be changed into a prime (21533342521) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 138616 + ... + 249561.

It is an arithmetic number, because the mean of its divisors is an integer number (1337661388).

Almost surely, 2^21533342721 is an apocalyptic number.

It is an amenable number.

21533342721 is a deficient number, since it is larger than the sum of its proper divisors (10570530591).

21533342721 is a wasteful number, since it uses less digits than its factorization.

21533342721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 388273 (or 388232 counting only the distinct ones).

The product of its digits is 30240, while the sum is 33.

The spelling of 21533342721 in words is "twenty-one billion, five hundred thirty-three million, three hundred forty-two thousand, seven hundred twenty-one".