21645717101718 has 8 divisors (see below), whose sum is σ = 43291434203448. Its totient is φ = 7215239033904.

The previous prime is 21645717101689. The next prime is 21645717101753. The reversal of 21645717101718 is 81710171754612.

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

21645717101718 is an admirable number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1803809758471 + ... + 1803809758482.

It is an arithmetic number, because the mean of its divisors is an integer number (5411429275431).

Almost surely, 2^{21645717101718} is an apocalyptic number.

21645717101718 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21645717101718 is a wasteful number, since it uses less digits than its factorization.

21645717101718 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3607619516958.

The product of its (nonzero) digits is 658560, while the sum is 51.

The spelling of 21645717101718 in words is "twenty-one trillion, six hundred forty-five billion, seven hundred seventeen million, one hundred one thousand, seven hundred eighteen".