21000140 has 24 divisors (see below), whose sum is σ = 50400672. Its totient is φ = 7200000.

The previous prime is 21000139. The next prime is 21000143. The reversal of 21000140 is 4100012.

It is not an unprimeable number, because it can be changed into a prime (21000143) 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, 74861 + ... + 75140.

It is an arithmetic number, because the mean of its divisors is an integer number (2100028).

Almost surely, 2^21000140 is an apocalyptic number.

21000140 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21000140 is an abundant number, since it is smaller than the sum of its proper divisors (29400532).

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

21000140 is a wasteful number, since it uses less digits than its factorization.

21000140 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 150017 (or 150015 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 8.

The square root of 21000140 is about 4582.5909701827. The cubic root of 21000140 is about 275.8930307310.

Adding to 21000140 its reverse (4100012), we get a palindrome (25100152).

The spelling of 21000140 in words is "twenty-one million, one hundred forty", and thus it is an aban number.