781791997 has 8 divisors (see below), whose sum is σ = 897968000. Its totient is φ = 666738864.

The previous prime is 781791991. The next prime is 781792009. The reversal of 781791997 is 799197187.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 781791997 - 2¹¹ = 781789949 is a prime.

It is a super-2 number, since 2×781791997² = 1222397453146496018, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (781791991) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 279222 + ... + 282007.

It is an arithmetic number, because the mean of its divisors is an integer number (112246000).

Almost surely, 2^781791997 is an apocalyptic number.

It is an amenable number.

781791997 is a deficient number, since it is larger than the sum of its proper divisors (116176003).

781791997 is a wasteful number, since it uses less digits than its factorization.

781791997 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 561435.

The product of its digits is 2000376, while the sum is 58.

The square root of 781791997 is about 27960.5435748306. The cubic root of 781791997 is about 921.2208103880.

The spelling of 781791997 in words is "seven hundred eighty-one million, seven hundred ninety-one thousand, nine hundred ninety-seven".