20783531 has 2 divisors, whose sum is σ = 20783532. Its totient is φ = 20783530.

The previous prime is 20783519. The next prime is 20783533. The reversal of 20783531 is 13538702.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20783531 - 2²² = 16589227 is a prime.

It is a super-2 number, since 2×20783531² = 863910321655922, which contains 22 as substring.

Together with 20783533, 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 = 20783494 and 20783503.

It is not a weakly prime, because it can be changed into another prime (20783533) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10391765 + 10391766.

It is an arithmetic number, because the mean of its divisors is an integer number (10391766).

Almost surely, 2^20783531 is an apocalyptic number.

20783531 is a deficient number, since it is larger than the sum of its proper divisors (1).

20783531 is an equidigital number, since it uses as much as digits as its factorization.

20783531 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5040, while the sum is 29.

The square root of 20783531 is about 4558.8958092942. The cubic root of 20783531 is about 274.9411708870.

It can be divided in two parts, 207 and 83531, that added together give a palindrome (83738).

The spelling of 20783531 in words is "twenty million, seven hundred eighty-three thousand, five hundred thirty-one".