21031000 has 32 divisors (see below), whose sum is σ = 49214880. Its totient is φ = 8412000.

The previous prime is 21030979. The next prime is 21031009. The reversal of 21031000 is 13012.

It is a super-2 number, since 2×21031000² = 884605922000000, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21031009) 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, 9516 + ... + 11515.

It is an arithmetic number, because the mean of its divisors is an integer number (1537965).

Almost surely, 2^21031000 is an apocalyptic number.

21031000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21031000 is an abundant number, since it is smaller than the sum of its proper divisors (28183880).

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

21031000 is a wasteful number, since it uses less digits than its factorization.

21031000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21052 (or 21038 counting only the distinct ones).

The product of its (nonzero) digits is 6, while the sum is 7.

The square root of 21031000 is about 4585.9568249167. The cubic root of 21031000 is about 276.0281074784.

Adding to 21031000 its reverse (13012), we get a palindrome (21044012).

The spelling of 21031000 in words is "twenty-one million, thirty-one thousand".