1978455864 has 384 divisors, whose sum is σ = 6823065600. Its totient is φ = 463034880.

The previous prime is 1978455863. The next prime is 1978455881. The reversal of 1978455864 is 4685548791.

It is a Harshad number since it is a multiple of its sum of digits (57).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1978455863) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 29529159 + ... + 29529225.

It is an arithmetic number, because the mean of its divisors is an integer number (17768400).

Almost surely, 2^1978455864 is an apocalyptic number.

1978455864 is a gapful number since it is divisible by the number (14) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1978455864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3411532800).

1978455864 is an abundant number, since it is smaller than the sum of its proper divisors (4844609736).

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

1978455864 is a wasteful number, since it uses less digits than its factorization.

1978455864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 171 (or 138 counting only the distinct ones).

The product of its digits is 9676800, while the sum is 57.

The square root of 1978455864 is about 44479.8366004193. The cubic root of 1978455864 is about 1255.3807226783.

The spelling of 1978455864 in words is "one billion, nine hundred seventy-eight million, four hundred fifty-five thousand, eight hundred sixty-four".