687979971 has 12 divisors (see below), whose sum is σ = 1135713072. Its totient is φ = 393131376.

The previous prime is 687979927. The next prime is 687979973. The reversal of 687979971 is 179979786.

It is not a de Polignac number, because 687979971 - 2¹⁴ = 687963587 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (63), and also a Moran number because the ratio is a prime number: 10920317 = 687979971 / (6 + 8 + 7 + 9 + 7 + 9 + 9 + 7 + 1).

It is a junction number, because it is equal to n+sod(n) for n = 687979899 and 687979908.

It is not an unprimeable number, because it can be changed into a prime (687979973) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5460096 + ... + 5460221.

It is an arithmetic number, because the mean of its divisors is an integer number (94642756).

Almost surely, 2^687979971 is an apocalyptic number.

687979971 is a deficient number, since it is larger than the sum of its proper divisors (447733101).

687979971 is a wasteful number, since it uses less digits than its factorization.

687979971 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10920330 (or 10920327 counting only the distinct ones).

The product of its digits is 12002256, while the sum is 63.

The square root of 687979971 is about 26229.3722951961. The cubic root of 687979971 is about 882.7924257284.

The spelling of 687979971 in words is "six hundred eighty-seven million, nine hundred seventy-nine thousand, nine hundred seventy-one".