21252777 has 16 divisors (see below), whose sum is σ = 34876800. Its totient is φ = 11210112.

The previous prime is 21252769. The next prime is 21252779. The reversal of 21252777 is 77725212.

It is not a de Polignac number, because 21252777 - 2³ = 21252769 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21252779) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 38652 + ... + 39197.

It is an arithmetic number, because the mean of its divisors is an integer number (2179800).

Almost surely, 2^21252777 is an apocalyptic number.

It is an amenable number.

21252777 is a deficient number, since it is larger than the sum of its proper divisors (13624023).

21252777 is a wasteful number, since it uses less digits than its factorization.

21252777 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77872.

The product of its digits is 13720, while the sum is 33.

The square root of 21252777 is about 4610.0734267471. The cubic root of 21252777 is about 276.9949779051.

Adding to 21252777 its reverse (77725212), we get a palindrome (98977989).

The spelling of 21252777 in words is "twenty-one million, two hundred fifty-two thousand, seven hundred seventy-seven".