21210372 has 36 divisors (see below), whose sum is σ = 53778816. Its totient is φ = 7048560.

The previous prime is 21210367. The next prime is 21210379. The reversal of 21210372 is 27301212.

It is a tau number, because it is divible by the number of its divisors (36).

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

It is not an unprimeable number, because it can be changed into a prime (21210379) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 14833 + ... + 16199.

It is an arithmetic number, because the mean of its divisors is an integer number (1493856).

Almost surely, 2^21210372 is an apocalyptic number.

It is an amenable number.

21210372 is an abundant number, since it is smaller than the sum of its proper divisors (32568444).

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

21210372 is a wasteful number, since it uses less digits than its factorization.

21210372 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1808 (or 1803 counting only the distinct ones).

The product of its (nonzero) digits is 168, while the sum is 18.

The square root of 21210372 is about 4605.4719627851. The cubic root of 21210372 is about 276.8106287754.

Adding to 21210372 its reverse (27301212), we get a palindrome (48511584).

The spelling of 21210372 in words is "twenty-one million, two hundred ten thousand, three hundred seventy-two".