21421434021 has 16 divisors (see below), whose sum is σ = 30766882944. Its totient is φ = 13179034944.

The previous prime is 21421433987. The next prime is 21421434029. The reversal of 21421434021 is 12043412412.

It is not a de Polignac number, because 21421434021 - 2¹⁰ = 21421432997 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21421433982 and 21421434000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21421434029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 87735 + ... + 224811.

It is an arithmetic number, because the mean of its divisors is an integer number (1922930184).

Almost surely, 2^21421434021 is an apocalyptic number.

It is an amenable number.

21421434021 is a deficient number, since it is larger than the sum of its proper divisors (9345448923).

21421434021 is a wasteful number, since it uses less digits than its factorization.

21421434021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 141100.

The product of its (nonzero) digits is 1536, while the sum is 24.

Adding to 21421434021 its reverse (12043412412), we get a palindrome (33464846433).

The spelling of 21421434021 in words is "twenty-one billion, four hundred twenty-one million, four hundred thirty-four thousand, twenty-one".