21518130 has 16 divisors (see below), whose sum is σ = 51643584. Its totient is φ = 5738160.

The previous prime is 21518111. The next prime is 21518131. The reversal of 21518130 is 3181512.

It is a junction number, because it is equal to n+sod(n) for n = 21518097 and 21518106.

It is not an unprimeable number, because it can be changed into a prime (21518131) 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 7 ways as a sum of consecutive naturals, for example, 358606 + ... + 358665.

It is an arithmetic number, because the mean of its divisors is an integer number (3227724).

Almost surely, 2^21518130 is an apocalyptic number.

21518130 is an abundant number, since it is smaller than the sum of its proper divisors (30125454).

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

21518130 is a wasteful number, since it uses less digits than its factorization.

21518130 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 717281.

The product of its (nonzero) digits is 240, while the sum is 21.

The square root of 21518130 is about 4638.7638439567. The cubic root of 21518130 is about 278.1430263113.

Adding to 21518130 its reverse (3181512), we get a palindrome (24699642).

The spelling of 21518130 in words is "twenty-one million, five hundred eighteen thousand, one hundred thirty".