78378721444 has 9 divisors (see below), whose sum is σ = 137163742401. Its totient is φ = 39189080760.

The previous prime is 78378721441. The next prime is 78378721501. The reversal of 78378721444 is 44412787387.

The square root of 78378721444 is 279962.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 135443044 + 78243278400 = 11638^2 + 279720^2 .

It is a super-2 number, since 2×78378721444² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78378721441) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 489934 + ... + 629914.

Almost surely, 2^78378721444 is an apocalyptic number.

78378721444 is the 279962-nd square number.

It is an amenable number.

78378721444 is a deficient number, since it is larger than the sum of its proper divisors (58785020957).

78378721444 is an frugal number, since it uses more digits than its factorization.

78378721444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 279966 (or 139983 counting only the distinct ones).

The product of its digits is 8429568, while the sum is 55.

The spelling of 78378721444 in words is "seventy-eight billion, three hundred seventy-eight million, seven hundred twenty-one thousand, four hundred forty-four".