21052777 has 4 divisors (see below), whose sum is σ = 21070036. Its totient is φ = 21035520.

The previous prime is 21052771. The next prime is 21052841. The reversal of 21052777 is 77725012.

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 17438976 + 3613801 = 4176^2 + 1901^2 .

It is a cyclic number.

It is not a de Polignac number, because 21052777 - 2³ = 21052769 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21052771) 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, 6648 + ... + 9289.

It is an arithmetic number, because the mean of its divisors is an integer number (5267509).

Almost surely, 2^21052777 is an apocalyptic number.

It is an amenable number.

21052777 is a deficient number, since it is larger than the sum of its proper divisors (17259).

21052777 is a wasteful number, since it uses less digits than its factorization.

21052777 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17258.

The product of its (nonzero) digits is 6860, while the sum is 31.

The square root of 21052777 is about 4588.3305242757. The cubic root of 21052777 is about 276.1233476878.

Adding to 21052777 its reverse (77725012), we get a palindrome (98777789).

The spelling of 21052777 in words is "twenty-one million, fifty-two thousand, seven hundred seventy-seven".