1645771878 has 16 divisors (see below), whose sum is σ = 3657270960. Its totient is φ = 548590608.

The previous prime is 1645771873. The next prime is 1645771879. The reversal of 1645771878 is 8781775461.

1645771878 is a `hidden beast` number, since 1 + 6 + 457 + 7 + 187 + 8 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54), and also a Moran number because the ratio is a prime number: 30477257 = 1645771878 / (1 + 6 + 4 + 5 + 7 + 7 + 1 + 8 + 7 + 8).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1645771873) 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, 15238575 + ... + 15238682.

It is an arithmetic number, because the mean of its divisors is an integer number (228579435).

Almost surely, 2^1645771878 is an apocalyptic number.

1645771878 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

1645771878 is an abundant number, since it is smaller than the sum of its proper divisors (2011499082).

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

1645771878 is a wasteful number, since it uses less digits than its factorization.

1645771878 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30477268 (or 30477262 counting only the distinct ones).

The product of its digits is 2634240, while the sum is 54.

The square root of 1645771878 is about 40568.1140552528. The cubic root of 1645771878 is about 1180.6555483161.

The spelling of 1645771878 in words is "one billion, six hundred forty-five million, seven hundred seventy-one thousand, eight hundred seventy-eight".