21400430021 has 4 divisors (see below), whose sum is σ = 21568937472. Its totient is φ = 21231922572.

The previous prime is 21400429949. The next prime is 21400430083. The reversal of 21400430021 is 12003400412.

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 not a de Polignac number, because 21400430021 - 2³⁴ = 4220560837 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 (21400430921) 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, 84253535 + ... + 84253788.

It is an arithmetic number, because the mean of its divisors is an integer number (5392234368).

Almost surely, 2^21400430021 is an apocalyptic number.

It is an amenable number.

21400430021 is a deficient number, since it is larger than the sum of its proper divisors (168507451).

21400430021 is a wasteful number, since it uses less digits than its factorization.

21400430021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 168507450.

The product of its (nonzero) digits is 192, while the sum is 17.

Adding to 21400430021 its reverse (12003400412), we get a palindrome (33403830433).

The spelling of 21400430021 in words is "twenty-one billion, four hundred million, four hundred thirty thousand, twenty-one".