21023140 has 12 divisors (see below), whose sum is σ = 44148636. Its totient is φ = 8409248.

The previous prime is 21023137. The next prime is 21023143. The reversal of 21023140 is 4132012.

It is an interprime number because it is at equal distance from previous prime (21023137) and next prime (21023143).

It can be written as a sum of positive squares in 2 ways, for example, as 11437924 + 9585216 = 3382^2 + 3096^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21023140.

It is not an unprimeable number, because it can be changed into a prime (21023143) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 525559 + ... + 525598.

It is an arithmetic number, because the mean of its divisors is an integer number (3679053).

Almost surely, 2^21023140 is an apocalyptic number.

21023140 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21023140 is an abundant number, since it is smaller than the sum of its proper divisors (23125496).

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

21023140 is a wasteful number, since it uses less digits than its factorization.

21023140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1051166 (or 1051164 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 13.

The square root of 21023140 is about 4585.0997808118. The cubic root of 21023140 is about 275.9937161630.

Adding to 21023140 its reverse (4132012), we get a palindrome (25155152).

The spelling of 21023140 in words is "twenty-one million, twenty-three thousand, one hundred forty".