19881971 has 2 divisors, whose sum is σ = 19881972. Its totient is φ = 19881970.

The previous prime is 19881947. The next prime is 19881973. The reversal of 19881971 is 17918891.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 19881971 - 2¹⁸ = 19619827 is a prime.

Together with 19881973, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (19881973) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9940985 + 9940986.

It is an arithmetic number, because the mean of its divisors is an integer number (9940986).

Almost surely, 2^19881971 is an apocalyptic number.

19881971 is a deficient number, since it is larger than the sum of its proper divisors (1).

19881971 is an equidigital number, since it uses as much as digits as its factorization.

19881971 is an evil number, because the sum of its binary digits is even.

The product of its digits is 36288, while the sum is 44.

The square root of 19881971 is about 4458.9203850260. The cubic root of 19881971 is about 270.9067411481.

The spelling of 19881971 in words is "nineteen million, eight hundred eighty-one thousand, nine hundred seventy-one".