21555740457 has 12 divisors (see below), whose sum is σ = 31142336004. Its totient is φ = 14367601440.

The previous prime is 21555740441. The next prime is 21555740543. The reversal of 21555740457 is 75404755512.

21555740457 is a `hidden beast` number, since 2 + 1 + 5 + 557 + 40 + 4 + 57 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 10763855001 + 10791885456 = 103749^2 + 103884^2 .

It is not a de Polignac number, because 21555740457 - 2⁴ = 21555740441 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21555740057) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 193318 + ... + 283695.

It is an arithmetic number, because the mean of its divisors is an integer number (2595194667).

Almost surely, 2^21555740457 is an apocalyptic number.

It is an amenable number.

21555740457 is a deficient number, since it is larger than the sum of its proper divisors (9586595547).

21555740457 is a wasteful number, since it uses less digits than its factorization.

21555740457 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 482040 (or 482037 counting only the distinct ones).

The product of its (nonzero) digits is 980000, while the sum is 45.

The spelling of 21555740457 in words is "twenty-one billion, five hundred fifty-five million, seven hundred forty thousand, four hundred fifty-seven".