20277721 has 8 divisors (see below), whose sum is σ = 20662280. Its totient is φ = 19896192.

The previous prime is 20277703. The next prime is 20277773. The reversal of 20277721 is 12777202.

It can be written as a sum of positive squares in 4 ways, for example, as 3013696 + 17264025 = 1736^2 + 4155^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20277721 is a prime.

It is a super-2 number, since 2×20277721² = 822371937907682, which contains 22 as substring.

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 20277721.

It is not an unprimeable number, because it can be changed into a prime (20277701) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16111 + ... + 17323.

It is an arithmetic number, because the mean of its divisors is an integer number (2582785).

Almost surely, 2^20277721 is an apocalyptic number.

It is an amenable number.

20277721 is a deficient number, since it is larger than the sum of its proper divisors (384559).

20277721 is a wasteful number, since it uses less digits than its factorization.

20277721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1515.

The product of its (nonzero) digits is 2744, while the sum is 28.

The square root of 20277721 is about 4503.0790577115. The cubic root of 20277721 is about 272.6924085096.

The spelling of 20277721 in words is "twenty million, two hundred seventy-seven thousand, seven hundred twenty-one".