2661665025 has 24 divisors (see below), whose sum is σ = 4402101184. Its totient is φ = 1419076800.

The previous prime is 2661665021. The next prime is 2661665047. The reversal of 2661665025 is 5205661662.

It is a happy number.

It is not a de Polignac number, because 2661665025 - 2² = 2661665021 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2661665021) 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, 411315 + ... + 417735.

Almost surely, 2^2661665025 is an apocalyptic number.

2661665025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

2661665025 is a deficient number, since it is larger than the sum of its proper divisors (1740436159).

2661665025 is a wasteful number, since it uses less digits than its factorization.

2661665025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11961 (or 11956 counting only the distinct ones).

The product of its (nonzero) digits is 129600, while the sum is 39.

The square root of 2661665025 is about 51591.3270327484. The cubic root of 2661665025 is about 1385.8550199315.

The spelling of 2661665025 in words is "two billion, six hundred sixty-one million, six hundred sixty-five thousand, twenty-five".