781649764 has 27 divisors (see below), whose sum is σ = 1592012793. Its totient is φ = 334825008.

The previous prime is 781649741. The next prime is 781649819. The reversal of 781649764 is 467946187.

The square root of 781649764 is 27958.

It is a perfect power (a square), and thus also a powerful number.

781649764 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 19448100 + 762201664 = 4410^2 + 27608^2 .

It is a super-2 number, since 2×781649764² = 1221952707122511392, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 390414 + ... + 392410.

Almost surely, 2^781649764 is an apocalyptic number.

781649764 is the 27958-th square number.

It is an amenable number.

781649764 is an abundant number, since it is smaller than the sum of its proper divisors (810363029).

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

781649764 is an equidigital number, since it uses as much as digits as its factorization.

781649764 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4012 (or 2006 counting only the distinct ones).

The product of its digits is 2032128, while the sum is 52.

The cubic root of 781649764 is about 921.1649404776.

The spelling of 781649764 in words is "seven hundred eighty-one million, six hundred forty-nine thousand, seven hundred sixty-four".