21231072 has 60 divisors (see below), whose sum is σ = 62447616. Its totient is φ = 7076160.

The previous prime is 21231029. The next prime is 21231107. The reversal of 21231072 is 27013212.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 1504 + ... + 6687.

Almost surely, 2^21231072 is an apocalyptic number.

It is an amenable number.

21231072 is an abundant number, since it is smaller than the sum of its proper divisors (41216544).

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

21231072 is an equidigital number, since it uses as much as digits as its factorization.

21231072 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8213 (or 8196 counting only the distinct ones).

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

The square root of 21231072 is about 4607.7187414164. The cubic root of 21231072 is about 276.9006494657.

Adding to 21231072 its reverse (27013212), we get a palindrome (48244284).

The spelling of 21231072 in words is "twenty-one million, two hundred thirty-one thousand, seventy-two".