21857735081 has 16 divisors (see below), whose sum is σ = 27204105600. Its totient is φ = 17099710848.

The previous prime is 21857735069. The next prime is 21857735083. The reversal of 21857735081 is 18053775812.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21857735081 - 2²² = 21853540777 is a prime.

It is a super-2 number, since 2×21857735081² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21857735083) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1341311 + ... + 1357508.

It is an arithmetic number, because the mean of its divisors is an integer number (1700256600).

Almost surely, 2^21857735081 is an apocalyptic number.

It is an amenable number.

21857735081 is a deficient number, since it is larger than the sum of its proper divisors (5346370519).

21857735081 is a wasteful number, since it uses less digits than its factorization.

21857735081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2698928.

The product of its (nonzero) digits is 470400, while the sum is 47.

The spelling of 21857735081 in words is "twenty-one billion, eight hundred fifty-seven million, seven hundred thirty-five thousand, eighty-one".