21098240 has 72 divisors (see below), whose sum is σ = 51655968. Its totient is φ = 8253440.

The previous prime is 21098221. The next prime is 21098257. The reversal of 21098240 is 4289012.

It is a congruent number.

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, 67685 + ... + 67995.

It is an arithmetic number, because the mean of its divisors is an integer number (717444).

Almost surely, 2^21098240 is an apocalyptic number.

21098240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21098240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25827984).

21098240 is an abundant number, since it is smaller than the sum of its proper divisors (30557728).

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

21098240 is an equidigital number, since it uses as much as digits as its factorization.

21098240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 385 (or 371 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 26.

The square root of 21098240 is about 4593.2820509958. The cubic root of 21098240 is about 276.3219655126.

The spelling of 21098240 in words is "twenty-one million, ninety-eight thousand, two hundred forty".