781400909 has 4 divisors (see below), whose sum is σ = 782167260. Its totient is φ = 780634560.

The previous prime is 781400881. The next prime is 781400923. The reversal of 781400909 is 909004187.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 532455625 + 248945284 = 23075^2 + 15778^2 .

It is a cyclic number.

It is not a de Polignac number, because 781400909 - 2²⁰ = 780352333 is a prime.

It is a super-2 number, since 2×781400909² = 1221174761172052562, 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 (781400959) 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 3 ways as a sum of consecutive naturals, for example, 381644 + ... + 383685.

It is an arithmetic number, because the mean of its divisors is an integer number (195541815).

Almost surely, 2^781400909 is an apocalyptic number.

It is an amenable number.

781400909 is a deficient number, since it is larger than the sum of its proper divisors (766351).

781400909 is a wasteful number, since it uses less digits than its factorization.

781400909 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 766350.

The product of its (nonzero) digits is 18144, while the sum is 38.

The square root of 781400909 is about 27953.5491306560. The cubic root of 781400909 is about 921.0671725499.

The spelling of 781400909 in words is "seven hundred eighty-one million, four hundred thousand, nine hundred nine".