21240385716555 has 160 divisors (see below), whose sum is σ = 40897982885760. Its totient is φ = 10507797135360.

The previous prime is 21240385716553. The next prime is 21240385716559. The reversal of 21240385716555 is 55561758304212.

21240385716555 is a `hidden beast` number, since 2 + 1 + 2 + 4 + 0 + 3 + 8 + 571 + 65 + 5 + 5 = 666.

It is not a de Polignac number, because 21240385716555 - 2¹ = 21240385716553 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21240385716553) by changing a digit.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 1689896311 + ... + 1689908879.

It is an arithmetic number, because the mean of its divisors is an integer number (255612393036).

Almost surely, 2^{21240385716555} is an apocalyptic number.

21240385716555 is a deficient number, since it is larger than the sum of its proper divisors (19657597169205).

21240385716555 is a wasteful number, since it uses less digits than its factorization.

21240385716555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16131 (or 16122 counting only the distinct ones).

The product of its (nonzero) digits is 10080000, while the sum is 54.

The spelling of 21240385716555 in words is "twenty-one trillion, two hundred forty billion, three hundred eighty-five million, seven hundred sixteen thousand, five hundred fifty-five".