21145751 has 8 divisors (see below), whose sum is σ = 23812608. Its totient is φ = 18603000.

The previous prime is 21145741. The next prime is 21145753. The reversal of 21145751 is 15754112.

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 21145751 - 2¹⁰ = 21144727 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21145751.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21145753) 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, 30665 + ... + 31346.

It is an arithmetic number, because the mean of its divisors is an integer number (2976576).

Almost surely, 2^21145751 is an apocalyptic number.

21145751 is a deficient number, since it is larger than the sum of its proper divisors (2666857).

21145751 is a wasteful number, since it uses less digits than its factorization.

21145751 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 62053.

The product of its digits is 1400, while the sum is 26.

The square root of 21145751 is about 4598.4509348258. The cubic root of 21145751 is about 276.5292259393.

Adding to 21145751 its reverse (15754112), we get a palindrome (36899863).

The spelling of 21145751 in words is "twenty-one million, one hundred forty-five thousand, seven hundred fifty-one".