21123758 has 16 divisors (see below), whose sum is σ = 33668784. Its totient is φ = 9905280.

The previous prime is 21123757. The next prime is 21123761. The reversal of 21123758 is 85732112.

It is a self number, because there is not a number n which added to its sum of digits gives 21123758.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21123757) 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 7 ways as a sum of consecutive naturals, for example, 10316 + ... + 12192.

It is an arithmetic number, because the mean of its divisors is an integer number (2104299).

Almost surely, 2^21123758 is an apocalyptic number.

21123758 is a deficient number, since it is larger than the sum of its proper divisors (12545026).

21123758 is a wasteful number, since it uses less digits than its factorization.

21123758 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2227.

The product of its digits is 3360, while the sum is 29.

The square root of 21123758 is about 4596.0589639386. The cubic root of 21123758 is about 276.4333230327.

The spelling of 21123758 in words is "twenty-one million, one hundred twenty-three thousand, seven hundred fifty-eight".