21231020 has 24 divisors (see below), whose sum is σ = 44998800. Its totient is φ = 8413632.

The previous prime is 21230969. The next prime is 21231029. The reversal of 21231020 is 2013212.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21230992 and 21231010.

It is not an unprimeable number, because it can be changed into a prime (21231029) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2690 + ... + 7049.

It is an arithmetic number, because the mean of its divisors is an integer number (1874950).

Almost surely, 2^21231020 is an apocalyptic number.

21231020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21231020 is an abundant number, since it is smaller than the sum of its proper divisors (23767780).

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

21231020 is a wasteful number, since it uses less digits than its factorization.

21231020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9857 (or 9855 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 11.

The square root of 21231020 is about 4607.7130987074. The cubic root of 21231020 is about 276.9004234001.

Adding to 21231020 its reverse (2013212), we get a palindrome (23244232).

The spelling of 21231020 in words is "twenty-one million, two hundred thirty-one thousand, twenty".