1691210988 has 72 divisors (see below), whose sum is σ = 4486966848. Its totient is φ = 556918416.

The previous prime is 1691210981. The next prime is 1691211007. The reversal of 1691210988 is 8890121961.

It is a super-2 number, since 2×1691210988² = 5720389211863872288, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1691210981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 70195 + ... + 91157.

It is an arithmetic number, because the mean of its divisors is an integer number (62318984).

Almost surely, 2^1691210988 is an apocalyptic number.

1691210988 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1691210988, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2243483424).

1691210988 is an abundant number, since it is smaller than the sum of its proper divisors (2795755860).

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

1691210988 is a wasteful number, since it uses less digits than its factorization.

1691210988 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21065 (or 21051 counting only the distinct ones).

The product of its (nonzero) digits is 62208, while the sum is 45.

The square root of 1691210988 is about 41124.3357149997. The cubic root of 1691210988 is about 1191.4228650270.

The spelling of 1691210988 in words is "one billion, six hundred ninety-one million, two hundred ten thousand, nine hundred eighty-eight".