21531150 has 96 divisors (see below), whose sum is σ = 60933600. Its totient is φ = 5587200.

The previous prime is 21531149. The next prime is 21531157. The reversal of 21531150 is 5113512.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21531157) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 55156 + ... + 55544.

It is an arithmetic number, because the mean of its divisors is an integer number (634725).

Almost surely, 2^21531150 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21531150, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30466800).

21531150 is an abundant number, since it is smaller than the sum of its proper divisors (39402450).

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

21531150 is a wasteful number, since it uses less digits than its factorization.

21531150 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 451 (or 440 counting only the distinct ones).

The product of its (nonzero) digits is 150, while the sum is 18.

The square root of 21531150 is about 4640.1670228560. The cubic root of 21531150 is about 278.1991137756.

Adding to 21531150 its reverse (5113512), we get a palindrome (26644662).

The spelling of 21531150 in words is "twenty-one million, five hundred thirty-one thousand, one hundred fifty".