638253561 has 32 divisors (see below), whose sum is σ = 960307200. Its totient is φ = 373726080.

The previous prime is 638253557. The next prime is 638253587. The reversal of 638253561 is 165352836.

It is not a de Polignac number, because 638253561 - 2² = 638253557 is a prime.

It is not an unprimeable number, because it can be changed into a prime (638253521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 119925 + ... + 125133.

It is an arithmetic number, because the mean of its divisors is an integer number (30009600).

Almost surely, 2^638253561 is an apocalyptic number.

It is an amenable number.

638253561 is a deficient number, since it is larger than the sum of its proper divisors (322053639).

638253561 is a wasteful number, since it uses less digits than its factorization.

638253561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5349.

The product of its digits is 129600, while the sum is 39.

The square root of 638253561 is about 25263.6806700845. The cubic root of 638253561 is about 860.9892892569.

The spelling of 638253561 in words is "six hundred thirty-eight million, two hundred fifty-three thousand, five hundred sixty-one".