780409890 has 120 divisors (see below), whose sum is σ = 2272668948. Its totient is φ = 192067200.

The previous prime is 780409879. The next prime is 780409897. The reversal of 780409890 is 98904087.

It can be written as a sum of positive squares in 6 ways, for example, as 190357209 + 590052681 = 13797^2 + 24291^2 .

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (780409897) 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 in 59 ways as a sum of consecutive naturals, for example, 134040 + ... + 139740.

Almost surely, 2^780409890 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 780409890, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1136334474).

780409890 is an abundant number, since it is smaller than the sum of its proper divisors (1492259058).

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

780409890 is a wasteful number, since it uses less digits than its factorization.

780409890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5746 (or 5724 counting only the distinct ones).

The product of its (nonzero) digits is 145152, while the sum is 45.

The square root of 780409890 is about 27935.8173318770. The cubic root of 780409890 is about 920.6776238061.

The spelling of 780409890 in words is "seven hundred eighty million, four hundred nine thousand, eight hundred ninety".