21765061 has 4 divisors (see below), whose sum is σ = 22711392. Its totient is φ = 20818732.

The previous prime is 21765047. The next prime is 21765071. The reversal of 21765061 is 16056712.

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 21765061 - 2⁷ = 21764933 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 (21765031) 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, 473131 + ... + 473176.

It is an arithmetic number, because the mean of its divisors is an integer number (5677848).

Almost surely, 2^21765061 is an apocalyptic number.

It is an amenable number.

21765061 is a deficient number, since it is larger than the sum of its proper divisors (946331).

21765061 is an equidigital number, since it uses as much as digits as its factorization.

21765061 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 946330.

The product of its (nonzero) digits is 2520, while the sum is 28.

The square root of 21765061 is about 4665.3039557997. The cubic root of 21765061 is about 279.2029244459.

The spelling of 21765061 in words is "twenty-one million, seven hundred sixty-five thousand, sixty-one".