1581643025 has 24 divisors (see below), whose sum is σ = 2079866880. Its totient is φ = 1189013760.

The previous prime is 1581643009. The next prime is 1581643027. The reversal of 1581643025 is 5203461851.

It is not a de Polignac number, because 1581643025 - 2⁴ = 1581643009 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1581643027) 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, 306416 + ... + 311534.

It is an arithmetic number, because the mean of its divisors is an integer number (86661120).

Almost surely, 2^1581643025 is an apocalyptic number.

It is an amenable number.

1581643025 is a deficient number, since it is larger than the sum of its proper divisors (498223855).

1581643025 is a wasteful number, since it uses less digits than its factorization.

1581643025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5873 (or 5868 counting only the distinct ones).

The product of its (nonzero) digits is 28800, while the sum is 35.

The square root of 1581643025 is about 39769.8758484358. The cubic root of 1581643025 is about 1165.1168689207.

The spelling of 1581643025 in words is "one billion, five hundred eighty-one million, six hundred forty-three thousand, twenty-five".