1921378365 has 48 divisors (see below), whose sum is σ = 3478550400. Its totient is φ = 980090496.

The previous prime is 1921378337. The next prime is 1921378397. The reversal of 1921378365 is 5638731291.

1921378365 is a `hidden beast` number, since 1 + 9 + 213 + 78 + 365 = 666.

1921378365 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 1921378365 - 2⁷ = 1921378237 is a prime.

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

It is a self number, because there is not a number n which added to its sum of digits gives 1921378365.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 88456 + ... + 108014.

It is an arithmetic number, because the mean of its divisors is an integer number (72469800).

Almost surely, 2^1921378365 is an apocalyptic number.

1921378365 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1921378365 is a deficient number, since it is larger than the sum of its proper divisors (1557172035).

1921378365 is a wasteful number, since it uses less digits than its factorization.

1921378365 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19666 (or 19663 counting only the distinct ones).

The product of its digits is 272160, while the sum is 45.

The square root of 1921378365 is about 43833.5301453123. The cubic root of 1921378365 is about 1243.1903548847.

The spelling of 1921378365 in words is "one billion, nine hundred twenty-one million, three hundred seventy-eight thousand, three hundred sixty-five".