636451997 has 2 divisors, whose sum is σ = 636451998. Its totient is φ = 636451996.

The previous prime is 636451993. The next prime is 636451999. The reversal of 636451997 is 799154636.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 635594521 + 857476 = 25211^2 + 926^2 .

It is a cyclic number.

It is not a de Polignac number, because 636451997 - 2² = 636451993 is a prime.

It is a super-2 number, since 2×636451997² = 810142288970576018, which contains 22 as substring.

Together with 636451999, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (636451993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 318225998 + 318225999.

It is an arithmetic number, because the mean of its divisors is an integer number (318225999).

Almost surely, 2^636451997 is an apocalyptic number.

It is an amenable number.

636451997 is a deficient number, since it is larger than the sum of its proper divisors (1).

636451997 is an equidigital number, since it uses as much as digits as its factorization.

636451997 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1224720, while the sum is 50.

The square root of 636451997 is about 25228.0002576502. Note that the first 3 decimals coincide. The cubic root of 636451997 is about 860.1784364739.

The spelling of 636451997 in words is "six hundred thirty-six million, four hundred fifty-one thousand, nine hundred ninety-seven".