20042531 has 4 divisors (see below), whose sum is σ = 20079072. Its totient is φ = 20005992.

The previous prime is 20042527. The next prime is 20042551. The reversal of 20042531 is 13524002.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 13524002 = 2 ⋅6762001.

It is a cyclic number.

It is not a de Polignac number, because 20042531 - 2² = 20042527 is a prime.

It is a super-2 number, since 2×20042531² = 803406097771922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20042521) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17435 + ... + 18548.

It is an arithmetic number, because the mean of its divisors is an integer number (5019768).

Almost surely, 2^20042531 is an apocalyptic number.

20042531 is a deficient number, since it is larger than the sum of its proper divisors (36541).

20042531 is an equidigital number, since it uses as much as digits as its factorization.

20042531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36540.

The product of its (nonzero) digits is 240, while the sum is 17.

The square root of 20042531 is about 4476.8885400465. Note that the first 3 decimals coincide. The cubic root of 20042531 is about 271.6340369223.

Adding to 20042531 its reverse (13524002), we get a palindrome (33566533).

The spelling of 20042531 in words is "twenty million, forty-two thousand, five hundred thirty-one".