21075767 has 4 divisors (see below), whose sum is σ = 22315536. Its totient is φ = 19836000.

The previous prime is 21075749. The next prime is 21075773. The reversal of 21075767 is 76757012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21075767 - 2¹⁴ = 21059383 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21075727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 619859 + ... + 619892.

It is an arithmetic number, because the mean of its divisors is an integer number (5578884).

Almost surely, 2^21075767 is an apocalyptic number.

21075767 is a deficient number, since it is larger than the sum of its proper divisors (1239769).

21075767 is a wasteful number, since it uses less digits than its factorization.

21075767 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1239768.

The product of its (nonzero) digits is 20580, while the sum is 35.

The square root of 21075767 is about 4590.8351092149. The cubic root of 21075767 is about 276.2238216289.

The spelling of 21075767 in words is "twenty-one million, seventy-five thousand, seven hundred sixty-seven".