639710661381 has 16 divisors (see below), whose sum is σ = 930611661888. Its totient is φ = 387652003200.

The previous prime is 639710661379. The next prime is 639710661407. The reversal of 639710661381 is 183166017936.

It is not a de Polignac number, because 639710661381 - 2¹ = 639710661379 is a prime.

It is a super-2 number, since 2×639710661381² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639710661311) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1032406 + ... + 1531431.

It is an arithmetic number, because the mean of its divisors is an integer number (58163228868).

Almost surely, 2^639710661381 is an apocalyptic number.

It is an amenable number.

639710661381 is a deficient number, since it is larger than the sum of its proper divisors (290901000507).

639710661381 is a wasteful number, since it uses less digits than its factorization.

639710661381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2571412.

The product of its (nonzero) digits is 979776, while the sum is 51.

The spelling of 639710661381 in words is "six hundred thirty-nine billion, seven hundred ten million, six hundred sixty-one thousand, three hundred eighty-one".