19551997 has 2 divisors, whose sum is σ = 19551998. Its totient is φ = 19551996.

The previous prime is 19551977. The next prime is 19552009. The reversal of 19551997 is 79915591.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16475481 + 3076516 = 4059^2 + 1754^2 .

It is a cyclic number.

It is not a de Polignac number, because 19551997 - 2¹⁵ = 19519229 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19551907) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9775998 + 9775999.

It is an arithmetic number, because the mean of its divisors is an integer number (9775999).

Almost surely, 2^19551997 is an apocalyptic number.

It is an amenable number.

19551997 is a deficient number, since it is larger than the sum of its proper divisors (1).

19551997 is an equidigital number, since it uses as much as digits as its factorization.

19551997 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 127575, while the sum is 46.

The square root of 19551997 is about 4421.7640145082. The cubic root of 19551997 is about 269.3996583640.

The spelling of 19551997 in words is "nineteen million, five hundred fifty-one thousand, nine hundred ninety-seven".