20251531 has 2 divisors, whose sum is σ = 20251532. Its totient is φ = 20251530.

The previous prime is 20251529. The next prime is 20251537. The reversal of 20251531 is 13515202.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20251531 - 2¹ = 20251529 is a prime.

It is a super-2 number, since 2×20251531² = 820249015687922, which contains 22 as substring.

Together with 20251529, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 20251499 and 20251508.

It is not a weakly prime, because it can be changed into another prime (20251537) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10125765 + 10125766.

It is an arithmetic number, because the mean of its divisors is an integer number (10125766).

Almost surely, 2^20251531 is an apocalyptic number.

20251531 is a deficient number, since it is larger than the sum of its proper divisors (1).

20251531 is an equidigital number, since it uses as much as digits as its factorization.

20251531 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 300, while the sum is 19.

The square root of 20251531 is about 4500.1701078959. The cubic root of 20251531 is about 272.5749579162.

Adding to 20251531 its reverse (13515202), we get a palindrome (33766733).

The spelling of 20251531 in words is "twenty million, two hundred fifty-one thousand, five hundred thirty-one".