21171023155 has 8 divisors (see below), whose sum is σ = 26091855792. Its totient is φ = 16479066528.

The previous prime is 21171023143. The next prime is 21171023183. The reversal of 21171023155 is 55132017112.

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 21171023155 - 2²³ = 21162634547 is a prime.

It is a super-3 number, since 3×21171023155³ (a number of 32 digits) contains 333 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 57218797 + ... + 57219166.

It is an arithmetic number, because the mean of its divisors is an integer number (3261481974).

Almost surely, 2^21171023155 is an apocalyptic number.

21171023155 is a deficient number, since it is larger than the sum of its proper divisors (4920832637).

21171023155 is a wasteful number, since it uses less digits than its factorization.

21171023155 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 114438005.

The product of its (nonzero) digits is 2100, while the sum is 28.

The spelling of 21171023155 in words is "twenty-one billion, one hundred seventy-one million, twenty-three thousand, one hundred fifty-five".