21125767 has 4 divisors (see below), whose sum is σ = 22750840. Its totient is φ = 19500696.

The previous prime is 21125761. The next prime is 21125789. The reversal of 21125767 is 76752112.

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 21125767 - 2⁷ = 21125639 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 (21125761) 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 3 ways as a sum of consecutive naturals, for example, 812517 + ... + 812542.

It is an arithmetic number, because the mean of its divisors is an integer number (5687710).

Almost surely, 2^21125767 is an apocalyptic number.

21125767 is a deficient number, since it is larger than the sum of its proper divisors (1625073).

21125767 is a wasteful number, since it uses less digits than its factorization.

21125767 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1625072.

The product of its digits is 5880, while the sum is 31.

The square root of 21125767 is about 4596.2775155554. The cubic root of 21125767 is about 276.4420862610.

Adding to 21125767 its reverse (76752112), we get a palindrome (97877879).

The spelling of 21125767 in words is "twenty-one million, one hundred twenty-five thousand, seven hundred sixty-seven".