691221384 has 128 divisors (see below), whose sum is σ = 2265292800. Its totient is φ = 191108160.

The previous prime is 691221371. The next prime is 691221397. The reversal of 691221384 is 483122196.

It is an interprime number because it is at equal distance from previous prime (691221371) and next prime (691221397).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

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 31 ways as a sum of consecutive naturals, for example, 39499 + ... + 54245.

It is an arithmetic number, because the mean of its divisors is an integer number (17697600).

Almost surely, 2^691221384 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 691221384, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1132646400).

691221384 is an abundant number, since it is smaller than the sum of its proper divisors (1574071416).

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

691221384 is a wasteful number, since it uses less digits than its factorization.

691221384 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14800 (or 14790 counting only the distinct ones).

The product of its digits is 20736, while the sum is 36.

The square root of 691221384 is about 26291.0894411015. The cubic root of 691221384 is about 884.1766775576.

The spelling of 691221384 in words is "six hundred ninety-one million, two hundred twenty-one thousand, three hundred eighty-four".