21208421436 has 24 divisors (see below), whose sum is σ = 49488888960. Its totient is φ = 7069106352.

The previous prime is 21208421413. The next prime is 21208421447. The reversal of 21208421436 is 63412480212.

It is a junction number, because it is equal to n+sod(n) for n = 21208421397 and 21208421406.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 296905 + ... + 361343.

It is an arithmetic number, because the mean of its divisors is an integer number (2062037040).

Almost surely, 2^21208421436 is an apocalyptic number.

It is an amenable number.

21208421436 is an abundant number, since it is smaller than the sum of its proper divisors (28280467524).

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

21208421436 is a wasteful number, since it uses less digits than its factorization.

21208421436 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 91873 (or 91871 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 33.

The spelling of 21208421436 in words is "twenty-one billion, two hundred eight million, four hundred twenty-one thousand, four hundred thirty-six".