21504130 has 16 divisors (see below), whose sum is σ = 38768184. Its totient is φ = 8588160.

The previous prime is 21504107. The next prime is 21504137. The reversal of 21504130 is 3140512.

It can be written as a sum of positive squares in 4 ways, for example, as 4190209 + 17313921 = 2047^2 + 4161^2 .

It is not an unprimeable number, because it can be changed into a prime (21504137) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7270 + ... + 9790.

Almost surely, 2^21504130 is an apocalyptic number.

21504130 is a deficient number, since it is larger than the sum of its proper divisors (17264054).

21504130 is a wasteful number, since it uses less digits than its factorization.

21504130 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3381.

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 21504130 is about 4637.2545757161. The cubic root of 21504130 is about 278.0826919611.

Adding to 21504130 its reverse (3140512), we get a palindrome (24644642).

The spelling of 21504130 in words is "twenty-one million, five hundred four thousand, one hundred thirty".