21090484 has 6 divisors (see below), whose sum is σ = 36908354. Its totient is φ = 10545240.

The previous prime is 21090473. The next prime is 21090491. The reversal of 21090484 is 48409012.

It can be written as a sum of positive squares in only one way, i.e., 15038884 + 6051600 = 3878^2 + 2460^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2636307 + ... + 2636314.

Almost surely, 2^21090484 is an apocalyptic number.

It is an amenable number.

21090484 is a deficient number, since it is larger than the sum of its proper divisors (15817870).

21090484 is a wasteful number, since it uses less digits than its factorization.

21090484 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5272625 (or 5272623 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 28.

The square root of 21090484 is about 4592.4376969100. The cubic root of 21090484 is about 276.2881014583.

Adding to 21090484 its reverse (48409012), we get a palindrome (69499496).

The spelling of 21090484 in words is "twenty-one million, ninety thousand, four hundred eighty-four".