21272777 has 4 divisors (see below), whose sum is σ = 21471696. Its totient is φ = 21073860.

The previous prime is 21272759. The next prime is 21272803. The reversal of 21272777 is 77727212.

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 a de Polignac number, because none of the positive numbers 2^k-21272777 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21272707) 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, 99299 + ... + 99512.

It is an arithmetic number, because the mean of its divisors is an integer number (5367924).

Almost surely, 2^21272777 is an apocalyptic number.

It is an amenable number.

21272777 is a deficient number, since it is larger than the sum of its proper divisors (198919).

21272777 is a wasteful number, since it uses less digits than its factorization.

21272777 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 198918.

The product of its digits is 19208, while the sum is 35.

The square root of 21272777 is about 4612.2420795097. The cubic root of 21272777 is about 277.0818396940.

Adding to 21272777 its reverse (77727212), we get a palindrome (98999989).

The spelling of 21272777 in words is "twenty-one million, two hundred seventy-two thousand, seven hundred seventy-seven".