20281765 has 32 divisors (see below), whose sum is σ = 29859840. Its totient is φ = 12908544.

The previous prime is 20281763. The next prime is 20281783. The reversal of 20281765 is 56718202.

It is a cyclic number.

It is not a de Polignac number, because 20281765 - 2¹ = 20281763 is a prime.

It is a super-2 number, since 2×20281765² = 822699983030450, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20281763) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 52764 + ... + 53146.

It is an arithmetic number, because the mean of its divisors is an integer number (933120).

Almost surely, 2^20281765 is an apocalyptic number.

It is an amenable number.

20281765 is a deficient number, since it is larger than the sum of its proper divisors (9578075).

20281765 is a wasteful number, since it uses less digits than its factorization.

20281765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 501.

The product of its (nonzero) digits is 6720, while the sum is 31.

The square root of 20281765 is about 4503.5280614203. The cubic root of 20281765 is about 272.7105350502.

Adding to 20281765 its reverse (56718202), we get a palindrome (76999967).

The spelling of 20281765 in words is "twenty million, two hundred eighty-one thousand, seven hundred sixty-five".