691393780 has 96 divisors (see below), whose sum is σ = 1833431040. Its totient is φ = 212734080.

The previous prime is 691393739. The next prime is 691393789. The reversal of 691393780 is 87393196.

It is a self number, because there is not a number n which added to its sum of digits gives 691393780.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (691393789) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 118819 + ... + 124501.

It is an arithmetic number, because the mean of its divisors is an integer number (19098240).

Almost surely, 2^691393780 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 691393780, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (916715520).

691393780 is an abundant number, since it is smaller than the sum of its proper divisors (1142037260).

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

691393780 is a wasteful number, since it uses less digits than its factorization.

691393780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5789 (or 5787 counting only the distinct ones).

The product of its (nonzero) digits is 244944, while the sum is 46.

The square root of 691393780 is about 26294.3678379991. The cubic root of 691393780 is about 884.2501782987.

The spelling of 691393780 in words is "six hundred ninety-one million, three hundred ninety-three thousand, seven hundred eighty".