781604 has 6 divisors (see below), whose sum is σ = 1367814. Its totient is φ = 390800.

The previous prime is 781601. The next prime is 781607. The reversal of 781604 is 406187.

It is an interprime number because it is at equal distance from previous prime (781601) and next prime (781607).

It can be written as a sum of positive squares in only one way, i.e., 719104 + 62500 = 848^2 + 250^2 .

It is a super-2 number, since 2×781604² = 1221809625632, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (781601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 97697 + ... + 97704.

It is an arithmetic number, because the mean of its divisors is an integer number (227969).

2⁷⁸¹⁶⁰⁴ is an apocalyptic number.

It is an amenable number.

781604 is a deficient number, since it is larger than the sum of its proper divisors (586210).

781604 is a wasteful number, since it uses less digits than its factorization.

781604 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 195405 (or 195403 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 26.

The square root of 781604 is about 884.0837064441. The cubic root of 781604 is about 92.1146962684.

The spelling of 781604 in words is "seven hundred eighty-one thousand, six hundred four".