21774161 has 4 divisors (see below), whose sum is σ = 23055012. Its totient is φ = 20493312.

The previous prime is 21774143. The next prime is 21774163. The reversal of 21774161 is 16147712.

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

It can be written as a sum of positive squares in 2 ways, for example, as 10758400 + 11015761 = 3280^2 + 3319^2 .

It is a cyclic number.

It is not a de Polignac number, because 21774161 - 2¹⁰ = 21773137 is a prime.

It is a super-2 number, since 2×21774161² = 948228174507842, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21774163) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 640400 + ... + 640433.

It is an arithmetic number, because the mean of its divisors is an integer number (5763753).

Almost surely, 2^21774161 is an apocalyptic number.

It is an amenable number.

21774161 is a deficient number, since it is larger than the sum of its proper divisors (1280851).

21774161 is a wasteful number, since it uses less digits than its factorization.

21774161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1280850.

The product of its digits is 2352, while the sum is 29.

The square root of 21774161 is about 4666.2791386714. The cubic root of 21774161 is about 279.2418307248.

The spelling of 21774161 in words is "twenty-one million, seven hundred seventy-four thousand, one hundred sixty-one".