21507753 has 8 divisors (see below), whose sum is σ = 30186400. Its totient is φ = 13583808.

The previous prime is 21507751. The next prime is 21507779. The reversal of 21507753 is 35770512.

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

It is not a de Polignac number, because 21507753 - 2¹ = 21507751 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 21507753.

It is not an unprimeable number, because it can be changed into a prime (21507751) 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, 188608 + ... + 188721.

It is an arithmetic number, because the mean of its divisors is an integer number (3773300).

Almost surely, 2^21507753 is an apocalyptic number.

It is an amenable number.

21507753 is a deficient number, since it is larger than the sum of its proper divisors (8678647).

21507753 is a wasteful number, since it uses less digits than its factorization.

21507753 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 377351.

The product of its (nonzero) digits is 7350, while the sum is 30.

The square root of 21507753 is about 4637.6451998832. The cubic root of 21507753 is about 278.0983081400.

Subtracting from 21507753 its product of nonzero digits (7350), we obtain a triangular number (21500403 = T₆₅₅₇).

The spelling of 21507753 in words is "twenty-one million, five hundred seven thousand, seven hundred fifty-three".