21195090 has 96 divisors (see below), whose sum is σ = 66718080. Its totient is φ = 4557312.

The previous prime is 21195077. The next prime is 21195091. The reversal of 21195090 is 9059112.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21195091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 9721 + ... + 11699.

It is an arithmetic number, because the mean of its divisors is an integer number (694980).

Almost surely, 2^21195090 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21195090, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33359040).

21195090 is an abundant number, since it is smaller than the sum of its proper divisors (45522990).

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

21195090 is a wasteful number, since it uses less digits than its factorization.

21195090 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2016 (or 2013 counting only the distinct ones).

The product of its (nonzero) digits is 810, while the sum is 27.

The square root of 21195090 is about 4603.8125504847. The cubic root of 21195090 is about 276.7441324344.

The spelling of 21195090 in words is "twenty-one million, one hundred ninety-five thousand, ninety".