21777145 has 8 divisors (see below), whose sum is σ = 28142856. Its totient is φ = 16081536.

The previous prime is 21777139. The next prime is 21777149. The reversal of 21777145 is 54177712.

It can be written as a sum of positive squares in 4 ways, for example, as 126736 + 21650409 = 356^2 + 4653^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 21777145 - 2¹³ = 21768953 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 21777145.

It is not an unprimeable number, because it can be changed into a prime (21777149) 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 7 ways as a sum of consecutive naturals, for example, 167452 + ... + 167581.

It is an arithmetic number, because the mean of its divisors is an integer number (3517857).

Almost surely, 2^21777145 is an apocalyptic number.

It is an amenable number.

21777145 is a deficient number, since it is larger than the sum of its proper divisors (6365711).

21777145 is a wasteful number, since it uses less digits than its factorization.

21777145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 335051.

The product of its digits is 13720, while the sum is 34.

The square root of 21777145 is about 4666.5988685551. The cubic root of 21777145 is about 279.2545862038.

The spelling of 21777145 in words is "twenty-one million, seven hundred seventy-seven thousand, one hundred forty-five".