21000726 has 24 divisors (see below), whose sum is σ = 45645600. Its totient is φ = 6978096.

The previous prime is 21000709. The next prime is 21000731. The reversal of 21000726 is 62700012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 21000699 and 21000708.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4611 + ... + 7953.

It is an arithmetic number, because the mean of its divisors is an integer number (1901900).

Almost surely, 2^21000726 is an apocalyptic number.

21000726 is an abundant number, since it is smaller than the sum of its proper divisors (24644874).

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

21000726 is a wasteful number, since it uses less digits than its factorization.

21000726 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3700 (or 3697 counting only the distinct ones).

The product of its (nonzero) digits is 168, while the sum is 18.

The square root of 21000726 is about 4582.6549073654. The cubic root of 21000726 is about 275.8955969331.

Adding to 21000726 its reverse (62700012), we get a palindrome (83700738).

The spelling of 21000726 in words is "twenty-one million, seven hundred twenty-six", and thus it is an aban number.