21372130 has 32 divisors (see below), whose sum is σ = 42865200. Its totient is φ = 7617792.

The previous prime is 21372103. The next prime is 21372133. The reversal of 21372130 is 3127312.

It is a Cunningham number, because it is equal to 4623²+1.

It can be written as a sum of positive squares in 8 ways, for example, as 3164841 + 18207289 = 1779^2 + 4267^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21372098 and 21372107.

It is not an unprimeable number, because it can be changed into a prime (21372133) 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 15 ways as a sum of consecutive naturals, for example, 936 + ... + 6604.

Almost surely, 2^21372130 is an apocalyptic number.

21372130 is an abundant number, since it is smaller than the sum of its proper divisors (21493070).

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

21372130 is a wasteful number, since it uses less digits than its factorization.

21372130 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5718.

The product of its (nonzero) digits is 252, while the sum is 19.

The square root of 21372130 is about 4623.0001081549. Note that the first 3 decimals coincide. The cubic root of 21372130 is about 277.5125335897.

Adding to 21372130 its reverse (3127312), we get a palindrome (24499442).

The spelling of 21372130 in words is "twenty-one million, three hundred seventy-two thousand, one hundred thirty".