21009552823 has 8 divisors (see below), whose sum is σ = 24244034048. Its totient is φ = 17833350744.

The previous prime is 21009552749. The next prime is 21009552847. The reversal of 21009552823 is 32825590012.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21009552823 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 (21009552023) 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 7 ways as a sum of consecutive naturals, for example, 14569011 + ... + 14570452.

It is an arithmetic number, because the mean of its divisors is an integer number (3030504256).

Almost surely, 2^21009552823 is an apocalyptic number.

21009552823 is a deficient number, since it is larger than the sum of its proper divisors (3234481225).

21009552823 is a wasteful number, since it uses less digits than its factorization.

21009552823 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29139573.

The product of its (nonzero) digits is 43200, while the sum is 37.

The spelling of 21009552823 in words is "twenty-one billion, nine million, five hundred fifty-two thousand, eight hundred twenty-three".