21398328 has 48 divisors (see below), whose sum is σ = 66234480. Its totient is φ = 6113664.

The previous prime is 21398327. The next prime is 21398341. The reversal of 21398328 is 82389312.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 21398292 and 21398301.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21398327) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 20725 + ... + 21732.

It is an arithmetic number, because the mean of its divisors is an integer number (1379885).

Almost surely, 2^21398328 is an apocalyptic number.

21398328 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21398328 is an abundant number, since it is smaller than the sum of its proper divisors (44836152).

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

21398328 is a wasteful number, since it uses less digits than its factorization.

21398328 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42476 (or 42469 counting only the distinct ones).

The product of its digits is 20736, while the sum is 36.

The square root of 21398328 is about 4625.8326817990. The cubic root of 21398328 is about 277.6258790968.

The spelling of 21398328 in words is "twenty-one million, three hundred ninety-eight thousand, three hundred twenty-eight".