21255000 has 160 divisors (see below), whose sum is σ = 72164400. Its totient is φ = 5184000.

The previous prime is 21254993. The next prime is 21255019. The reversal of 21255000 is 55212.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 194946 + ... + 195054.

Almost surely, 2^21255000 is an apocalyptic number.

21255000 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 21255000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36082200).

21255000 is an abundant number, since it is smaller than the sum of its proper divisors (50909400).

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

21255000 is a wasteful number, since it uses less digits than its factorization.

21255000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 151 (or 132 counting only the distinct ones).

The product of its (nonzero) digits is 100, while the sum is 15.

The square root of 21255000 is about 4610.3145228932. The cubic root of 21255000 is about 277.0046352841.

The spelling of 21255000 in words is "twenty-one million, two hundred fifty-five thousand".