21331240421 has 4 divisors (see below), whose sum is σ = 21499203072. Its totient is φ = 21163277772.

The previous prime is 21331240391. The next prime is 21331240453. The reversal of 21331240421 is 12404213312.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21331240421 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21331240471) 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, 83981135 + ... + 83981388.

It is an arithmetic number, because the mean of its divisors is an integer number (5374800768).

Almost surely, 2^21331240421 is an apocalyptic number.

It is an amenable number.

21331240421 is a deficient number, since it is larger than the sum of its proper divisors (167962651).

21331240421 is a wasteful number, since it uses less digits than its factorization.

21331240421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 167962650.

The product of its (nonzero) digits is 1152, while the sum is 23.

Adding to 21331240421 its reverse (12404213312), we get a palindrome (33735453733).

The spelling of 21331240421 in words is "twenty-one billion, three hundred thirty-one million, two hundred forty thousand, four hundred twenty-one".