21780487617858 has 24 divisors (see below), whose sum is σ = 47209144401900. Its totient is φ = 7257379785984.

The previous prime is 21780487617857. The next prime is 21780487617899. The reversal of 21780487617858 is 85871678408712.

21780487617858 is a `hidden beast` number, since 2 + 1 + 7 + 8 + 0 + 487 + 61 + 7 + 85 + 8 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 19098534414969 + 2681953202889 = 4370187^2 + 1637667^2 .

It is not an unprimeable number, because it can be changed into a prime (21780487617857) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 231847843 + ... + 231941766.

Almost surely, 2^{21780487617858} is an apocalyptic number.

21780487617858 is an abundant number, since it is smaller than the sum of its proper divisors (25428656784042).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21780487617858 is a wasteful number, since it uses less digits than its factorization.

21780487617858 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 463792226 (or 463792223 counting only the distinct ones).

The product of its (nonzero) digits is 337182720, while the sum is 72.

The spelling of 21780487617858 in words is "twenty-one trillion, seven hundred eighty billion, four hundred eighty-seven million, six hundred seventeen thousand, eight hundred fifty-eight".