20122781 has 30 divisors (see below), whose sum is σ = 25797210. Its totient is φ = 15673728.

The previous prime is 20122763. The next prime is 20122787. The reversal of 20122781 is 18722102.

It can be written as a sum of positive squares in 3 ways, for example, as 8357881 + 11764900 = 2891^2 + 3430^2 .

It is not a de Polignac number, because 20122781 - 2¹⁴ = 20106397 is a prime.

It is a super-2 number, since 2×20122781² = 809852630347922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20122787) by changing a digit.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 693875 + ... + 693903.

It is an arithmetic number, because the mean of its divisors is an integer number (859907).

Almost surely, 2^20122781 is an apocalyptic number.

It is an amenable number.

20122781 is a deficient number, since it is larger than the sum of its proper divisors (5674429).

20122781 is an frugal number, since it uses more digits than its factorization.

20122781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91 (or 53 counting only the distinct ones).

The product of its (nonzero) digits is 448, while the sum is 23.

The square root of 20122781 is about 4485.8422843430. The cubic root of 20122781 is about 271.9960936939.

Adding to 20122781 its reverse (18722102), we get a palindrome (38844883).

The spelling of 20122781 in words is "twenty million, one hundred twenty-two thousand, seven hundred eighty-one".