21117650551 has 4 divisors (see below), whose sum is σ = 21283931392. Its totient is φ = 20951369712.

The previous prime is 21117650503. The next prime is 21117650599. The reversal of 21117650551 is 15505671112.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (21117650503) and next prime (21117650599).

It is a cyclic number.

It is not a de Polignac number, because 21117650551 - 2⁹ = 21117650039 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 (21117653551) 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, 83140230 + ... + 83140483.

It is an arithmetic number, because the mean of its divisors is an integer number (5320982848).

Almost surely, 2^21117650551 is an apocalyptic number.

21117650551 is a deficient number, since it is larger than the sum of its proper divisors (166280841).

21117650551 is a wasteful number, since it uses less digits than its factorization.

21117650551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 166280840.

The product of its (nonzero) digits is 10500, while the sum is 34.

The spelling of 21117650551 in words is "twenty-one billion, one hundred seventeen million, six hundred fifty thousand, five hundred fifty-one".