20787971 has 2 divisors, whose sum is σ = 20787972. Its totient is φ = 20787970.

The previous prime is 20787961. The next prime is 20788003. The reversal of 20787971 is 17978702.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20787971 - 2¹⁰ = 20786947 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20787901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10393985 + 10393986.

It is an arithmetic number, because the mean of its divisors is an integer number (10393986).

Almost surely, 2^20787971 is an apocalyptic number.

20787971 is a deficient number, since it is larger than the sum of its proper divisors (1).

20787971 is an equidigital number, since it uses as much as digits as its factorization.

20787971 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 49392, while the sum is 41.

The square root of 20787971 is about 4559.3827433108. The cubic root of 20787971 is about 274.9607481167.

The spelling of 20787971 in words is "twenty million, seven hundred eighty-seven thousand, nine hundred seventy-one".