21055000 has 40 divisors (see below), whose sum is σ = 49343580. Its totient is φ = 8420000.

The previous prime is 21054973. The next prime is 21055003. The reversal of 21055000 is 55012.

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21055003) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 2895 + ... + 7105.

Almost surely, 2^21055000 is an apocalyptic number.

21055000 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 21055000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24671790).

21055000 is an abundant number, since it is smaller than the sum of its proper divisors (28288580).

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

21055000 is an equidigital number, since it uses as much as digits as its factorization.

21055000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4237 (or 4218 counting only the distinct ones).

The product of its (nonzero) digits is 50, while the sum is 13.

The square root of 21055000 is about 4588.5727628534. The cubic root of 21055000 is about 276.1330661301.

The spelling of 21055000 in words is "twenty-one million, fifty-five thousand".