21040756 has 12 divisors (see below), whose sum is σ = 40168800. Its totient is φ = 9563960.

The previous prime is 21040741. The next prime is 21040759. The reversal of 21040756 is 65704012.

It is a self number, because there is not a number n which added to its sum of digits gives 21040756.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21040759) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 239056 + ... + 239143.

It is an arithmetic number, because the mean of its divisors is an integer number (3347400).

Almost surely, 2^21040756 is an apocalyptic number.

It is an amenable number.

21040756 is a deficient number, since it is larger than the sum of its proper divisors (19128044).

21040756 is a wasteful number, since it uses less digits than its factorization.

21040756 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 478214 (or 478212 counting only the distinct ones).

The product of its (nonzero) digits is 1680, while the sum is 25.

The square root of 21040756 is about 4587.0203836478. The cubic root of 21040756 is about 276.0707827977.

Adding to 21040756 its reverse (65704012), we get a palindrome (86744768).

The spelling of 21040756 in words is "twenty-one million, forty thousand, seven hundred fifty-six".