637681 has 8 divisors (see below), whose sum is σ = 720000. Its totient is φ = 559440.

The previous prime is 637669. The next prime is 637691. The reversal of 637681 is 186736.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 637681 - 2¹⁷ = 506609 is a prime.

It is a super-2 number, since 2×637681² = 813274115522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (637601) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 681 + ... + 1318.

It is an arithmetic number, because the mean of its divisors is an integer number (90000).

2⁶³⁷⁶⁸¹ is an apocalyptic number.

It is an amenable number.

637681 is a deficient number, since it is larger than the sum of its proper divisors (82319).

637681 is a wasteful number, since it uses less digits than its factorization.

637681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2039.

The product of its digits is 6048, while the sum is 31.

The square root of 637681 is about 798.5493096860. The cubic root of 637681 is about 86.0731755051.

It can be divided in two parts, 63 and 7681, that added together give a square (7744 = 88²).

The spelling of 637681 in words is "six hundred thirty-seven thousand, six hundred eighty-one".