21519090 has 48 divisors (see below), whose sum is σ = 56301336. Its totient is φ = 5702400.

The previous prime is 21519083. The next prime is 21519101. The reversal of 21519090 is 9091512.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 15657849 + 5861241 = 3957^2 + 2421^2 .

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 15630 + ... + 16950.

Almost surely, 2^21519090 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21519090, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28150668).

21519090 is an abundant number, since it is smaller than the sum of its proper divisors (34782246).

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

21519090 is a wasteful number, since it uses less digits than its factorization.

21519090 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1515 (or 1512 counting only the distinct ones).

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

The square root of 21519090 is about 4638.8673186458. The cubic root of 21519090 is about 278.1471625650.

The spelling of 21519090 in words is "twenty-one million, five hundred nineteen thousand, ninety".