21409284 has 24 divisors (see below), whose sum is σ = 53798080. Its totient is φ = 6587424.

The previous prime is 21409277. The next prime is 21409291. The reversal of 21409284 is 48290412.

It is an interprime number because it is at equal distance from previous prime (21409277) and next prime (21409291).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 68464 + ... + 68775.

Almost surely, 2^21409284 is an apocalyptic number.

It is an amenable number.

21409284 is an abundant number, since it is smaller than the sum of its proper divisors (32388796).

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

21409284 is a wasteful number, since it uses less digits than its factorization.

21409284 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 137259 (or 137257 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 30.

The square root of 21409284 is about 4627.0167494834. The cubic root of 21409284 is about 277.6732527384.

Adding to 21409284 its reverse (48290412), we get a palindrome (69699696).

The spelling of 21409284 in words is "twenty-one million, four hundred nine thousand, two hundred eighty-four".