21012755 has 8 divisors (see below), whose sum is σ = 25250400. Its totient is φ = 16786816.

The previous prime is 21012749. The next prime is 21012773. The reversal of 21012755 is 55721012.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21012755 - 2²⁰ = 19964179 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21012755.

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, 1691 + ... + 6699.

It is an arithmetic number, because the mean of its divisors is an integer number (3156300).

Almost surely, 2^21012755 is an apocalyptic number.

21012755 is a deficient number, since it is larger than the sum of its proper divisors (4237645).

21012755 is an equidigital number, since it uses as much as digits as its factorization.

21012755 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5853.

The product of its (nonzero) digits is 700, while the sum is 23.

The square root of 21012755 is about 4583.9671682943. The cubic root of 21012755 is about 275.9482635995.

Adding to 21012755 its reverse (55721012), we get a palindrome (76733767).

The spelling of 21012755 in words is "twenty-one million, twelve thousand, seven hundred fifty-five".