21655550055681 has 24 divisors (see below), whose sum is σ = 31320813363840. Its totient is φ = 14418318103200.

The previous prime is 21655550055653. The next prime is 21655550055691. The reversal of 21655550055681 is 18655005555612.

21655550055681 is a `hidden beast` number, since 2 + 1 + 6 + 5 + 5 + 5 + 5 + 0 + 0 + 556 + 81 = 666.

It is not a de Polignac number, because 21655550055681 - 2⁶ = 21655550055617 is a prime.

It is a super-2 number, since 2×21655550055681² (a number of 27 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21655550055631) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 22450086 + ... + 23394816.

It is an arithmetic number, because the mean of its divisors is an integer number (1305033890160).

Almost surely, 2^{21655550055681} is an apocalyptic number.

It is an amenable number.

21655550055681 is a deficient number, since it is larger than the sum of its proper divisors (9665263308159).

21655550055681 is a wasteful number, since it uses less digits than its factorization.

21655550055681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 948037 (or 948034 counting only the distinct ones).

The product of its (nonzero) digits is 9000000, while the sum is 54.

The spelling of 21655550055681 in words is "twenty-one trillion, six hundred fifty-five billion, five hundred fifty million, fifty-five thousand, six hundred eighty-one".