21365740 has 24 divisors (see below), whose sum is σ = 48947472. Its totient is φ = 7769280.

The previous prime is 21365737. The next prime is 21365741. The reversal of 21365740 is 4756312.

It is a junction number, because it is equal to n+sod(n) for n = 21365699 and 21365708.

It is not an unprimeable number, because it can be changed into a prime (21365741) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 48339 + ... + 48778.

It is an arithmetic number, because the mean of its divisors is an integer number (2039478).

Almost surely, 2^21365740 is an apocalyptic number.

21365740 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21365740 is an abundant number, since it is smaller than the sum of its proper divisors (27581732).

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

21365740 is a wasteful number, since it uses less digits than its factorization.

21365740 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 97137 (or 97135 counting only the distinct ones).

The product of its (nonzero) digits is 5040, while the sum is 28.

The square root of 21365740 is about 4622.3089468360. The cubic root of 21365740 is about 277.4848732387.

The spelling of 21365740 in words is "twenty-one million, three hundred sixty-five thousand, seven hundred forty".