21375000 has 168 divisors, whose sum is σ = 76170900. Its totient is φ = 5400000.

The previous prime is 21374971. The next prime is 21375007. The reversal of 21375000 is 57312.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21375007) by changing a digit.

It is a polite number, since it can be written in 41 ways as a sum of consecutive naturals, for example, 1124991 + ... + 1125009.

It is a vampire number, since it can be written as 3000 ⋅ 7125 (with its own digits).

Almost surely, 2^21375000 is an apocalyptic number.

21375000 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 21375000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38085450).

21375000 is an abundant number, since it is smaller than the sum of its proper divisors (54795900).

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

21375000 is an equidigital number, since it uses as much as digits as its factorization.

21375000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61 (or 29 counting only the distinct ones).

The product of its (nonzero) digits is 210, while the sum is 18.

The square root of 21375000 is about 4623.3105022267. The cubic root of 21375000 is about 277.5249551456.

The spelling of 21375000 in words is "twenty-one million, three hundred seventy-five thousand".