21001533320 has 32 divisors (see below), whose sum is σ = 48405976920. Its totient is φ = 8195719680.

The previous prime is 21001533313. The next prime is 21001533323. The reversal of 21001533320 is 2333510012.

It can be written as a sum of positive squares in 4 ways, for example, as 16110209476 + 4891323844 = 126926^2 + 69938^2 .

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 21001533292 and 21001533301.

It is not an unprimeable number, because it can be changed into a prime (21001533323) 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, 6401267 + ... + 6404546.

Almost surely, 2^21001533320 is an apocalyptic number.

21001533320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21001533320 is an abundant number, since it is smaller than the sum of its proper divisors (27404443600).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21001533320 is a wasteful number, since it uses less digits than its factorization.

21001533320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12805865 (or 12805861 counting only the distinct ones).

The product of its (nonzero) digits is 540, while the sum is 20.

The spelling of 21001533320 in words is "twenty-one billion, one million, five hundred thirty-three thousand, three hundred twenty".