21553856909 has 8 divisors (see below), whose sum is σ = 23491507872. Its totient is φ = 19656157680.

The previous prime is 21553856887. The next prime is 21553856923. The reversal of 21553856909 is 90965835512.

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 21553856909 - 2²⁴ = 21537079693 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21553856939) 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, 9986807 + ... + 9988964.

It is an arithmetic number, because the mean of its divisors is an integer number (2936438484).

Almost surely, 2^21553856909 is an apocalyptic number.

It is an amenable number.

21553856909 is a deficient number, since it is larger than the sum of its proper divisors (1937650963).

21553856909 is a wasteful number, since it uses less digits than its factorization.

21553856909 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19975867.

The product of its (nonzero) digits is 2916000, while the sum is 53.

The spelling of 21553856909 in words is "twenty-one billion, five hundred fifty-three million, eight hundred fifty-six thousand, nine hundred nine".