20428281 has 12 divisors (see below), whose sum is σ = 30600752. Its totient is φ = 13618692.

The previous prime is 20428277. The next prime is 20428283. The reversal of 20428281 is 18282402.

It is not a de Polignac number, because 20428281 - 2² = 20428277 is a prime.

It is a super-2 number, since 2×20428281² = 834629329229922, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20428283) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 41791 + ... + 42276.

Almost surely, 2^20428281 is an apocalyptic number.

It is an amenable number.

20428281 is a deficient number, since it is larger than the sum of its proper divisors (10172471).

20428281 is an frugal number, since it uses more digits than its factorization.

20428281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84082 (or 84070 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 27.

The square root of 20428281 is about 4519.7655912669. The cubic root of 20428281 is about 273.3656493948.

The spelling of 20428281 in words is "twenty million, four hundred twenty-eight thousand, two hundred eighty-one".