21458728868 has 6 divisors (see below), whose sum is σ = 37552775526. Its totient is φ = 10729364432.

The previous prime is 21458728849. The next prime is 21458728909. The reversal of 21458728868 is 86882785412.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 21430617664 + 28111204 = 146392^2 + 5302^2 .

It is a super-2 number, since 2×21458728868² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2682341105 + ... + 2682341112.

It is an arithmetic number, because the mean of its divisors is an integer number (6258795921).

Almost surely, 2^21458728868 is an apocalyptic number.

It is an amenable number.

21458728868 is a deficient number, since it is larger than the sum of its proper divisors (16094046658).

21458728868 is a wasteful number, since it uses less digits than its factorization.

21458728868 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5364682221 (or 5364682219 counting only the distinct ones).

The product of its digits is 13762560, while the sum is 59.

The spelling of 21458728868 in words is "twenty-one billion, four hundred fifty-eight million, seven hundred twenty-eight thousand, eight hundred sixty-eight".