21121753 has 4 divisors (see below), whose sum is σ = 21571200. Its totient is φ = 20672308.

The previous prime is 21121741. The next prime is 21121759. The reversal of 21121753 is 35712112.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21121753 - 2⁹ = 21121241 is a prime.

It is a super-2 number, since 2×21121753² = 892256899586018, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21121759) 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, 224653 + ... + 224746.

It is an arithmetic number, because the mean of its divisors is an integer number (5392800).

Almost surely, 2^21121753 is an apocalyptic number.

It is an amenable number.

21121753 is a deficient number, since it is larger than the sum of its proper divisors (449447).

21121753 is an equidigital number, since it uses as much as digits as its factorization.

21121753 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 449446.

The product of its digits is 420, while the sum is 22.

The square root of 21121753 is about 4595.8408371048. The cubic root of 21121753 is about 276.4245766984.

Adding to 21121753 its reverse (35712112), we get a palindrome (56833865).

The spelling of 21121753 in words is "twenty-one million, one hundred twenty-one thousand, seven hundred fifty-three".