21478808 has 16 divisors (see below), whose sum is σ = 43370880. Its totient is φ = 9913248.

The previous prime is 21478799. The next prime is 21478817. The reversal of 21478808 is 80887412.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21478799) and next prime (21478817).

It is a super-2 number, since 2×21478808² = 922678386201728, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 103160 + ... + 103367.

It is an arithmetic number, because the mean of its divisors is an integer number (2710680).

Almost surely, 2^21478808 is an apocalyptic number.

It is an amenable number.

21478808 is an abundant number, since it is smaller than the sum of its proper divisors (21892072).

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

21478808 is a wasteful number, since it uses less digits than its factorization.

21478808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 206546 (or 206542 counting only the distinct ones).

The product of its (nonzero) digits is 28672, while the sum is 38.

The square root of 21478808 is about 4634.5234922266. The cubic root of 21478808 is about 277.9734978100.

The spelling of 21478808 in words is "twenty-one million, four hundred seventy-eight thousand, eight hundred eight".