1978722720 has 144 divisors (see below), whose sum is σ = 7271874792. Its totient is φ = 487065600.

The previous prime is 1978722703. The next prime is 1978722727. The reversal of 1978722720 is 272278791.

1978722720 is digitally balanced in base 4, 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 4 ways, for example, as 892097424 + 1086625296 = 29868^2 + 32964^2 .

It is a tau number, because it is divible by the number of its divisors (144).

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

It is not an unprimeable number, because it can be changed into a prime (1978722727) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 34131 + ... + 71570.

Almost surely, 2^1978722720 is an apocalyptic number.

1978722720 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1978722720 is an abundant number, since it is smaller than the sum of its proper divisors (5293152072).

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

1978722720 is a wasteful number, since it uses less digits than its factorization.

1978722720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 105735 (or 105724 counting only the distinct ones).

The product of its (nonzero) digits is 197568, while the sum is 45.

The square root of 1978722720 is about 44482.8362405097. The cubic root of 1978722720 is about 1255.4371624542.

The spelling of 1978722720 in words is "one billion, nine hundred seventy-eight million, seven hundred twenty-two thousand, seven hundred twenty".