21055233421 has 8 divisors (see below), whose sum is σ = 21477676184. Its totient is φ = 20635283520.

The previous prime is 21055233403. The next prime is 21055233427. The reversal of 21055233421 is 12433255012.

It can be written as a sum of positive squares in 4 ways, for example, as 1135016100 + 19920217321 = 33690^2 + 141139^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21055233421 - 2⁷ = 21055233293 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21055233421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21055233427) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 606150 + ... + 639943.

It is an arithmetic number, because the mean of its divisors is an integer number (2684709523).

Almost surely, 2^21055233421 is an apocalyptic number.

It is an amenable number.

21055233421 is a deficient number, since it is larger than the sum of its proper divisors (422442763).

21055233421 is a wasteful number, since it uses less digits than its factorization.

21055233421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1246431.

The product of its (nonzero) digits is 7200, while the sum is 28.

Adding to 21055233421 its reverse (12433255012), we get a palindrome (33488488433).

The spelling of 21055233421 in words is "twenty-one billion, fifty-five million, two hundred thirty-three thousand, four hundred twenty-one".