1681691690 has 32 divisors (see below), whose sum is σ = 3609895680. Its totient is φ = 551510784.

The previous prime is 1681691677. The next prime is 1681691707. The reversal of 1681691690 is 961961861.

It is a super-2 number, since 2×1681691690² = 5656173880430112200, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 520655 + ... + 523874.

It is an arithmetic number, because the mean of its divisors is an integer number (112809240).

Almost surely, 2^1681691690 is an apocalyptic number.

1681691690 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1681691690 is an abundant number, since it is smaller than the sum of its proper divisors (1928203990).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1681691690 is a wasteful number, since it uses less digits than its factorization.

1681691690 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1044566.

The product of its (nonzero) digits is 139968, while the sum is 47.

The square root of 1681691690 is about 41008.4343763573. The cubic root of 1681691690 is about 1189.1832754786.

The spelling of 1681691690 in words is "one billion, six hundred eighty-one million, six hundred ninety-one thousand, six hundred ninety".