19899947 has 2 divisors, whose sum is σ = 19899948. Its totient is φ = 19899946.

The previous prime is 19899889. The next prime is 19899949. The reversal of 19899947 is 74999891.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 19899947 - 2¹⁶ = 19834411 is a prime.

Together with 19899949, 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 = 19899892 and 19899901.

It is not a weakly prime, because it can be changed into another prime (19899949) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9949973 + 9949974.

It is an arithmetic number, because the mean of its divisors is an integer number (9949974).

Almost surely, 2^19899947 is an apocalyptic number.

19899947 is a deficient number, since it is larger than the sum of its proper divisors (1).

19899947 is an equidigital number, since it uses as much as digits as its factorization.

19899947 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1469664, while the sum is 56.

The square root of 19899947 is about 4460.9356641853. The cubic root of 19899947 is about 270.9883620407.

Subtracting from 19899947 its sum of digits (56), we obtain a palindrome (19899891).

The spelling of 19899947 in words is "nineteen million, eight hundred ninety-nine thousand, nine hundred forty-seven".