21554415443421 has 48 divisors (see below), whose sum is σ = 35802007063680. Its totient is φ = 12240622903680.

The previous prime is 21554415443333. The next prime is 21554415443479. The reversal of 21554415443421 is 12434451445512.

21554415443421 is a `hidden beast` number, since 2 + 1 + 5 + 5 + 44 + 154 + 434 + 21 = 666.

It is not a de Polignac number, because 21554415443421 - 2⁷ = 21554415443293 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21554415443621) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 266758495 + ... + 266839283.

It is an arithmetic number, because the mean of its divisors is an integer number (745875147160).

Almost surely, 2^{21554415443421} is an apocalyptic number.

21554415443421 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21554415443421 is a deficient number, since it is larger than the sum of its proper divisors (14247591620259).

21554415443421 is a wasteful number, since it uses less digits than its factorization.

21554415443421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 106946 (or 106943 counting only the distinct ones).

The product of its digits is 1536000, while the sum is 45.

Adding to 21554415443421 its reverse (12434451445512), we get a palindrome (33988866888933).

The spelling of 21554415443421 in words is "twenty-one trillion, five hundred fifty-four billion, four hundred fifteen million, four hundred forty-three thousand, four hundred twenty-one".