1688974661 has 4 divisors (see below), whose sum is σ = 1842517824. Its totient is φ = 1535431500.

The previous prime is 1688974601. The next prime is 1688974673. The reversal of 1688974661 is 1664798861.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1688974661 - 2²⁶ = 1621865797 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1688974597 and 1688974606.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1688974601) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 76771565 + ... + 76771586.

It is an arithmetic number, because the mean of its divisors is an integer number (460629456).

Almost surely, 2^1688974661 is an apocalyptic number.

1688974661 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1688974661 is a deficient number, since it is larger than the sum of its proper divisors (153543163).

1688974661 is a wasteful number, since it uses less digits than its factorization.

1688974661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 153543162.

The product of its digits is 3483648, while the sum is 56.

The square root of 1688974661 is about 41097.1368954091. The cubic root of 1688974661 is about 1190.8974848097.

The spelling of 1688974661 in words is "one billion, six hundred eighty-eight million, nine hundred seventy-four thousand, six hundred sixty-one".