21330340421 has 4 divisors (see below), whose sum is σ = 22971135852. Its totient is φ = 19689544992.

The previous prime is 21330340417. The next prime is 21330340433. The reversal of 21330340421 is 12404303312.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1197852100 + 20132488321 = 34610^2 + 141889^2 .

It is not a de Polignac number, because 21330340421 - 2² = 21330340417 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21330340721) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 820397696 + ... + 820397721.

It is an arithmetic number, because the mean of its divisors is an integer number (5742783963).

Almost surely, 2^21330340421 is an apocalyptic number.

It is an amenable number.

21330340421 is a deficient number, since it is larger than the sum of its proper divisors (1640795431).

21330340421 is a wasteful number, since it uses less digits than its factorization.

21330340421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1640795430.

The product of its (nonzero) digits is 1728, while the sum is 23.

Adding to 21330340421 its reverse (12404303312), we get a palindrome (33734643733).

The spelling of 21330340421 in words is "twenty-one billion, three hundred thirty million, three hundred forty thousand, four hundred twenty-one".