21207140 has 12 divisors (see below), whose sum is σ = 44535036. Its totient is φ = 8482848.

The previous prime is 21207133. The next prime is 21207161. The reversal of 21207140 is 4170212.

It can be written as a sum of positive squares in 2 ways, for example, as 6522916 + 14684224 = 2554^2 + 3832^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 530159 + ... + 530198.

It is an arithmetic number, because the mean of its divisors is an integer number (3711253).

Almost surely, 2^21207140 is an apocalyptic number.

21207140 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21207140 is an abundant number, since it is smaller than the sum of its proper divisors (23327896).

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

21207140 is a wasteful number, since it uses less digits than its factorization.

21207140 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1060366 (or 1060364 counting only the distinct ones).

The product of its (nonzero) digits is 112, while the sum is 17.

The square root of 21207140 is about 4605.1210624695. The cubic root of 21207140 is about 276.7965680854.

Adding to 21207140 its reverse (4170212), we get a palindrome (25377352).

The spelling of 21207140 in words is "twenty-one million, two hundred seven thousand, one hundred forty".