638261621407 has 4 divisors (see below), whose sum is σ = 642545256600. Its totient is φ = 633977986216.

The previous prime is 638261621381. The next prime is 638261621467. The reversal of 638261621407 is 704126162836.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 638261621407 - 2²⁷ = 638127403679 is a prime.

It is a super-2 number, since 2×638261621407² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638261621467) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2141817373 + ... + 2141817670.

It is an arithmetic number, because the mean of its divisors is an integer number (160636314150).

Almost surely, 2^638261621407 is an apocalyptic number.

638261621407 is a deficient number, since it is larger than the sum of its proper divisors (4283635193).

638261621407 is a wasteful number, since it uses less digits than its factorization.

638261621407 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4283635192.

The product of its (nonzero) digits is 580608, while the sum is 46.

The spelling of 638261621407 in words is "six hundred thirty-eight billion, two hundred sixty-one million, six hundred twenty-one thousand, four hundred seven".