1625776661 has 4 divisors (see below), whose sum is σ = 1630905612. Its totient is φ = 1620647712.

The previous prime is 1625776651. The next prime is 1625776703. The reversal of 1625776661 is 1666775261.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 262764100 + 1363012561 = 16210^2 + 36919^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1625776661 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1625776651) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2564000 + ... + 2564633.

It is an arithmetic number, because the mean of its divisors is an integer number (407726403).

Almost surely, 2^1625776661 is an apocalyptic number.

It is an amenable number.

1625776661 is a deficient number, since it is larger than the sum of its proper divisors (5128951).

1625776661 is an equidigital number, since it uses as much as digits as its factorization.

1625776661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5128950.

The product of its digits is 635040, while the sum is 47.

The square root of 1625776661 is about 40320.9208848211. The cubic root of 1625776661 is about 1175.8546155617.

The spelling of 1625776661 in words is "one billion, six hundred twenty-five million, seven hundred seventy-six thousand, six hundred sixty-one".