1645250661 has 6 divisors (see below), whose sum is σ = 2376473190. Its totient is φ = 1096833768.

The previous prime is 1645250657. The next prime is 1645250681. The reversal of 1645250661 is 1660525461.

1645250661 is a `hidden beast` number, since 1 + 645 + 2 + 5 + 0 + 6 + 6 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 904866561 + 740384100 = 30081^2 + 27210^2 .

It is not a de Polignac number, because 1645250661 - 2² = 1645250657 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1645250611) 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, 91402806 + ... + 91402823.

It is an arithmetic number, because the mean of its divisors is an integer number (396078865).

Almost surely, 2^1645250661 is an apocalyptic number.

It is an amenable number.

1645250661 is a deficient number, since it is larger than the sum of its proper divisors (731222529).

1645250661 is a wasteful number, since it uses less digits than its factorization.

1645250661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 182805635 (or 182805632 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 36.

The square root of 1645250661 is about 40561.6895727976. The cubic root of 1645250661 is about 1180.5308970352.

The spelling of 1645250661 in words is "one billion, six hundred forty-five million, two hundred fifty thousand, six hundred sixty-one".