21131530 has 32 divisors (see below), whose sum is σ = 43831296. Its totient is φ = 7185024.

The previous prime is 21131519. The next prime is 21131531. The reversal of 21131530 is 3513112.

It is not an unprimeable number, because it can be changed into a prime (21131531) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7702 + ... + 10078.

It is an arithmetic number, because the mean of its divisors is an integer number (1369728).

Almost surely, 2^21131530 is an apocalyptic number.

21131530 is an abundant number, since it is smaller than the sum of its proper divisors (22699766).

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

21131530 is a wasteful number, since it uses less digits than its factorization.

21131530 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2518.

The product of its (nonzero) digits is 90, while the sum is 16.

The square root of 21131530 is about 4596.9043931759. The cubic root of 21131530 is about 276.4672212995.

Adding to 21131530 its reverse (3513112), we get a palindrome (24644642).

The spelling of 21131530 in words is "twenty-one million, one hundred thirty-one thousand, five hundred thirty".