21554434420 has 12 divisors (see below), whose sum is σ = 45264312324. Its totient is φ = 8621773760.

The previous prime is 21554434417. The next prime is 21554434427. The reversal of 21554434420 is 2443445512.

It can be written as a sum of positive squares in 2 ways, for example, as 10444431204 + 11110003216 = 102198^2 + 105404^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21554434427) 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, 538860841 + ... + 538860880.

It is an arithmetic number, because the mean of its divisors is an integer number (3772026027).

Almost surely, 2^21554434420 is an apocalyptic number.

21554434420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21554434420 is an abundant number, since it is smaller than the sum of its proper divisors (23709877904).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21554434420 is a wasteful number, since it uses less digits than its factorization.

21554434420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1077721730 (or 1077721728 counting only the distinct ones).

The product of its (nonzero) digits is 76800, while the sum is 34.

Adding to 21554434420 its reverse (2443445512), we get a palindrome (23997879932).

The spelling of 21554434420 in words is "twenty-one billion, five hundred fifty-four million, four hundred thirty-four thousand, four hundred twenty".