21161759 has 4 divisors (see below), whose sum is σ = 21252816. Its totient is φ = 21070704.

The previous prime is 21161737. The next prime is 21161761. The reversal of 21161759 is 95716112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21161759 - 2²⁴ = 4384543 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21161729) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 45179 + ... + 45644.

It is an arithmetic number, because the mean of its divisors is an integer number (5313204).

Almost surely, 2^21161759 is an apocalyptic number.

21161759 is a deficient number, since it is larger than the sum of its proper divisors (91057).

21161759 is an equidigital number, since it uses as much as digits as its factorization.

21161759 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91056.

The product of its digits is 3780, while the sum is 32.

The square root of 21161759 is about 4600.1911916789. The cubic root of 21161759 is about 276.5989887847.

The spelling of 21161759 in words is "twenty-one million, one hundred sixty-one thousand, seven hundred fifty-nine".