21000340 has 24 divisors (see below), whose sum is σ = 45128160. Its totient is φ = 8204448.

The previous prime is 21000337. The next prime is 21000367. The reversal of 21000340 is 4300012.

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11350 + ... + 13069.

It is an arithmetic number, because the mean of its divisors is an integer number (1880340).

Almost surely, 2^21000340 is an apocalyptic number.

21000340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21000340 is an abundant number, since it is smaller than the sum of its proper divisors (24127820).

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

21000340 is a wasteful number, since it uses less digits than its factorization.

21000340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24471 (or 24469 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 10.

The square root of 21000340 is about 4582.6127918470. The cubic root of 21000340 is about 275.8939065733.

Adding to 21000340 its reverse (4300012), we get a palindrome (25300352).

The spelling of 21000340 in words is "twenty-one million, three hundred forty", and thus it is an aban number.