18877997 has 2 divisors, whose sum is σ = 18877998. Its totient is φ = 18877996.

The previous prime is 18877993. The next prime is 18878003. The reversal of 18877997 is 79977881.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18826921 + 51076 = 4339^2 + 226^2 .

It is a cyclic number.

It is not a de Polignac number, because 18877997 - 2² = 18877993 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18877993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9438998 + 9438999.

It is an arithmetic number, because the mean of its divisors is an integer number (9438999).

Almost surely, 2^18877997 is an apocalyptic number.

It is an amenable number.

18877997 is a deficient number, since it is larger than the sum of its proper divisors (1).

18877997 is an equidigital number, since it uses as much as digits as its factorization.

18877997 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1778112, while the sum is 56.

The square root of 18877997 is about 4344.8817014966. The cubic root of 18877997 is about 266.2677923852.

The spelling of 18877997 in words is "eighteen million, eight hundred seventy-seven thousand, nine hundred ninety-seven".