20671531 has 2 divisors, whose sum is σ = 20671532. Its totient is φ = 20671530.

The previous prime is 20671529. The next prime is 20671543. The reversal of 20671531 is 13517602.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20671531 - 2¹ = 20671529 is a prime.

It is a super-2 number, since 2×20671531² = 854624387767922, which contains 22 as substring.

Together with 20671529, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 20671496 and 20671505.

It is not a weakly prime, because it can be changed into another prime (20671331) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10335765 + 10335766.

It is an arithmetic number, because the mean of its divisors is an integer number (10335766).

Almost surely, 2^20671531 is an apocalyptic number.

20671531 is a deficient number, since it is larger than the sum of its proper divisors (1).

20671531 is an equidigital number, since it uses as much as digits as its factorization.

20671531 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1260, while the sum is 25.

The square root of 20671531 is about 4546.5955395219. The cubic root of 20671531 is about 274.4464058836.

The spelling of 20671531 in words is "twenty million, six hundred seventy-one thousand, five hundred thirty-one".