21055433657 has 16 divisors (see below), whose sum is σ = 22452681600. Its totient is φ = 19676128512.

The previous prime is 21055433653. The next prime is 21055433671. The reversal of 21055433657 is 75633455012.

It is a cyclic number.

It is not a de Polignac number, because 21055433657 - 2² = 21055433653 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21055433653) 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, 2416094 + ... + 2424792.

It is an arithmetic number, because the mean of its divisors is an integer number (1403292600).

Almost surely, 2^21055433657 is an apocalyptic number.

It is an amenable number.

21055433657 is a deficient number, since it is larger than the sum of its proper divisors (1397247943).

21055433657 is a wasteful number, since it uses less digits than its factorization.

21055433657 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9712.

The product of its (nonzero) digits is 378000, while the sum is 41.

Adding to 21055433657 its reverse (75633455012), we get a palindrome (96688888669).

The spelling of 21055433657 in words is "twenty-one billion, fifty-five million, four hundred thirty-three thousand, six hundred fifty-seven".