21404567808 has 432 divisors, whose sum is σ = 71139833856. Its totient is φ = 6131220480.

The previous prime is 21404567803. The next prime is 21404567813. The reversal of 21404567808 is 80876540412.

21404567808 is a `hidden beast` number, since 2 + 1 + 4 + 0 + 4 + 567 + 80 + 8 = 666.

It is a Cunningham number, because it is equal to 146303²-1.

It is an interprime number because it is at equal distance from previous prime (21404567803) and next prime (21404567813).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21404567801) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 64666203 + ... + 64666533.

Almost surely, 2^21404567808 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21404567808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35569916928).

21404567808 is an abundant number, since it is smaller than the sum of its proper divisors (49735266048).

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

21404567808 is a wasteful number, since it uses less digits than its factorization.

21404567808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 510 (or 493 counting only the distinct ones).

The product of its (nonzero) digits is 430080, while the sum is 45.

The spelling of 21404567808 in words is "twenty-one billion, four hundred four million, five hundred sixty-seven thousand, eight hundred eight".