1981548905625 has 75 divisors (see below), whose sum is σ = 3602950650013. Its totient is φ = 1049112024000.

The previous prime is 1981548905569. The next prime is 1981548905701. The reversal of 1981548905625 is 5265098451891.

The square root of 1981548905625 is 1407675.

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

1981548905625 is a `hidden beast` number, since 1 + 9 + 81 + 5 + 489 + 0 + 56 + 25 = 666.

It can be written as a sum of positive squares in 12 ways, for example, as 1958491090521 + 23057815104 = 1399461^2 + 151848^2 .

It is a tau number, because it is divible by the number of its divisors (75).

It is a de Polignac number, because none of the positive numbers 2^k-1981548905625 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 74 ways as a sum of consecutive naturals, for example, 14463860557 + ... + 14463860693.

Almost surely, 2^{1981548905625} is an apocalyptic number.

1981548905625 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1981548905625 is the 1407675-th square number.

1981548905625 is the 703838-th centered octagonal number.

It is an amenable number.

1981548905625 is a deficient number, since it is larger than the sum of its proper divisors (1621401744388).

1981548905625 is an frugal number, since it uses more digits than its factorization.

1981548905625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 574 (or 145 counting only the distinct ones).

The product of its (nonzero) digits is 31104000, while the sum is 63.

The spelling of 1981548905625 in words is "one trillion, nine hundred eighty-one billion, five hundred forty-eight million, nine hundred five thousand, six hundred twenty-five".