21330021990 has 32 divisors (see below), whose sum is σ = 51535634400. Its totient is φ = 5649830144.

The previous prime is 21330021959. The next prime is 21330021991. The reversal of 21330021990 is 9912003312.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21330021991) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2381439 + ... + 2390378.

It is an arithmetic number, because the mean of its divisors is an integer number (1610488575).

Almost surely, 2^21330021990 is an apocalyptic number.

21330021990 is an abundant number, since it is smaller than the sum of its proper divisors (30205612410).

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

21330021990 is a wasteful number, since it uses less digits than its factorization.

21330021990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4771976.

The product of its (nonzero) digits is 2916, while the sum is 30.

The spelling of 21330021990 in words is "twenty-one billion, three hundred thirty million, twenty-one thousand, nine hundred ninety".