21125751 has 8 divisors (see below), whose sum is σ = 28216944. Its totient is φ = 14059200.

The previous prime is 21125749. The next prime is 21125761. The reversal of 21125751 is 15752112.

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

It is not a de Polignac number, because 21125751 - 2¹ = 21125749 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21125711) 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 7 ways as a sum of consecutive naturals, for example, 4056 + ... + 7661.

It is an arithmetic number, because the mean of its divisors is an integer number (3527118).

Almost surely, 2^21125751 is an apocalyptic number.

21125751 is a deficient number, since it is larger than the sum of its proper divisors (7091193).

21125751 is a wasteful number, since it uses less digits than its factorization.

21125751 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12321.

The product of its digits is 700, while the sum is 24.

The square root of 21125751 is about 4596.2757750161. The cubic root of 21125751 is about 276.4420164715.

Adding to 21125751 its reverse (15752112), we get a palindrome (36877863).

The spelling of 21125751 in words is "twenty-one million, one hundred twenty-five thousand, seven hundred fifty-one".