20642281 has 8 divisors (see below), whose sum is σ = 22944384. Its totient is φ = 18411120.

The previous prime is 20642273. The next prime is 20642291. The reversal of 20642281 is 18224602.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 20642281 - 2³ = 20642273 is a prime.

It is a super-2 number, since 2×20642281² = 852207529765922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20642291) 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, 17121 + ... + 18286.

It is an arithmetic number, because the mean of its divisors is an integer number (2868048).

Almost surely, 2^20642281 is an apocalyptic number.

It is an amenable number.

20642281 is a deficient number, since it is larger than the sum of its proper divisors (2302103).

20642281 is a wasteful number, since it uses less digits than its factorization.

20642281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35471.

The product of its (nonzero) digits is 1536, while the sum is 25.

The square root of 20642281 is about 4543.3777082695. The cubic root of 20642281 is about 274.3168985166.

Adding to 20642281 its reverse (18224602), we get a palindrome (38866883).

The spelling of 20642281 in words is "twenty million, six hundred forty-two thousand, two hundred eighty-one".