21784564258 has 4 divisors (see below), whose sum is σ = 32676846390. Its totient is φ = 10892282128.

The previous prime is 21784564253. The next prime is 21784564273. The reversal of 21784564258 is 85246548712.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 20911184449 + 873379809 = 144607^2 + 29553^2 .

It is not an unprimeable number, because it can be changed into a prime (21784564253) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5446141063 + ... + 5446141066.

Almost surely, 2^21784564258 is an apocalyptic number.

21784564258 is a deficient number, since it is larger than the sum of its proper divisors (10892282132).

21784564258 is a wasteful number, since it uses less digits than its factorization.

21784564258 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10892282131.

The product of its digits is 4300800, while the sum is 52.

The spelling of 21784564258 in words is "twenty-one billion, seven hundred eighty-four million, five hundred sixty-four thousand, two hundred fifty-eight".