18021123656 has 8 divisors (see below), whose sum is σ = 33789606870. Its totient is φ = 9010561824.

The previous prime is 18021123619. The next prime is 18021123671. The reversal of 18021123656 is 65632112081.

It can be written as a sum of positive squares in only one way, i.e., 11721526756 + 6299596900 = 108266^2 + 79370^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1126320221 + ... + 1126320236.

Almost surely, 2^18021123656 is an apocalyptic number.

It is an amenable number.

18021123656 is a deficient number, since it is larger than the sum of its proper divisors (15768483214).

18021123656 is a wasteful number, since it uses less digits than its factorization.

18021123656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2252640463 (or 2252640459 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 35.

The spelling of 18021123656 in words is "eighteen billion, twenty-one million, one hundred twenty-three thousand, six hundred fifty-six".