19903997 has 2 divisors, whose sum is σ = 19903998. Its totient is φ = 19903996.

The previous prime is 19903979. The next prime is 19904051. The reversal of 19903997 is 79930991.

It is a happy number.

Together with previous prime (19903979) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19882681 + 21316 = 4459^2 + 146^2 .

It is a cyclic number.

It is not a de Polignac number, because 19903997 - 2¹⁴ = 19887613 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19903937) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9951998 + 9951999.

It is an arithmetic number, because the mean of its divisors is an integer number (9951999).

Almost surely, 2^19903997 is an apocalyptic number.

It is an amenable number.

19903997 is a deficient number, since it is larger than the sum of its proper divisors (1).

19903997 is an equidigital number, since it uses as much as digits as its factorization.

19903997 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 137781, while the sum is 47.

The square root of 19903997 is about 4461.3895817335. The cubic root of 19903997 is about 271.0067444752.

The spelling of 19903997 in words is "nineteen million, nine hundred three thousand, nine hundred ninety-seven".