21820424456 has 8 divisors (see below), whose sum is σ = 40913295870. Its totient is φ = 10910212224.

The previous prime is 21820424449. The next prime is 21820424503. The reversal of 21820424456 is 65442402812.

It can be written as a sum of positive squares in only one way, i.e., 17442484900 + 4377939556 = 132070^2 + 66166^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is a super-2 number, since 2×21820424456² (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 (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1363776521 + ... + 1363776536.

Almost surely, 2^21820424456 is an apocalyptic number.

It is an amenable number.

21820424456 is a deficient number, since it is larger than the sum of its proper divisors (19092871414).

21820424456 is a wasteful number, since it uses less digits than its factorization.

21820424456 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2727553063 (or 2727553059 counting only the distinct ones).

The product of its (nonzero) digits is 122880, while the sum is 38.

The spelling of 21820424456 in words is "twenty-one billion, eight hundred twenty million, four hundred twenty-four thousand, four hundred fifty-six".