21778545718 has 4 divisors (see below), whose sum is σ = 32667818580. Its totient is φ = 10889272858.

The previous prime is 21778545713. The next prime is 21778545727. The reversal of 21778545718 is 81754587712.

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

It is a super-2 number, since 2×21778545718² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21778545713) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5444636428 + ... + 5444636431.

It is an arithmetic number, because the mean of its divisors is an integer number (8166954645).

Almost surely, 2^21778545718 is an apocalyptic number.

21778545718 is a deficient number, since it is larger than the sum of its proper divisors (10889272862).

21778545718 is a wasteful number, since it uses less digits than its factorization.

21778545718 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10889272861.

The product of its digits is 4390400, while the sum is 55.

The spelling of 21778545718 in words is "twenty-one billion, seven hundred seventy-eight million, five hundred forty-five thousand, seven hundred eighteen".