1821660725 has 6 divisors (see below), whose sum is σ = 2258859330. Its totient is φ = 1457328560.

The previous prime is 1821660713. The next prime is 1821660727. The reversal of 1821660725 is 5270661281.

It can be written as a sum of positive squares in 3 ways, for example, as 356378884 + 1465281841 = 18878^2 + 38279^2 .

It is not a de Polignac number, because 1821660725 - 2²⁰ = 1820612149 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1821660727) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 36433190 + ... + 36433239.

It is an arithmetic number, because the mean of its divisors is an integer number (376476555).

Almost surely, 2^1821660725 is an apocalyptic number.

It is an amenable number.

1821660725 is a deficient number, since it is larger than the sum of its proper divisors (437198605).

1821660725 is an equidigital number, since it uses as much as digits as its factorization.

1821660725 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72866439 (or 72866434 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 38.

The square root of 1821660725 is about 42680.9175744852. The cubic root of 1821660725 is about 1221.3003972097.

The spelling of 1821660725 in words is "one billion, eight hundred twenty-one million, six hundred sixty thousand, seven hundred twenty-five".