21153434421 has 16 divisors (see below), whose sum is σ = 32238708224. Its totient is φ = 12085838064.

The previous prime is 21153434413. The next prime is 21153434453. The reversal of 21153434421 is 12443435112.

It is not a de Polignac number, because 21153434421 - 2³ = 21153434413 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 (21153434411) 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, 71370 + ... + 217716.

It is an arithmetic number, because the mean of its divisors is an integer number (2014919264).

Almost surely, 2^21153434421 is an apocalyptic number.

21153434421 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21153434421 is a deficient number, since it is larger than the sum of its proper divisors (11085273803).

21153434421 is a wasteful number, since it uses less digits than its factorization.

21153434421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 153240.

The product of its digits is 11520, while the sum is 30.

Adding to 21153434421 its reverse (12443435112), we get a palindrome (33596869533).

The spelling of 21153434421 in words is "twenty-one billion, one hundred fifty-three million, four hundred thirty-four thousand, four hundred twenty-one".