1645078761 has 32 divisors (see below), whose sum is σ = 2466777600. Its totient is φ = 1083471120.

The previous prime is 1645078723. The next prime is 1645078777. The reversal of 1645078761 is 1678705461.

1645078761 is a `hidden beast` number, since 1 + 6 + 4 + 507 + 87 + 61 = 666.

It is not a de Polignac number, because 1645078761 - 2¹⁸ = 1644816617 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1645078781) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 850966 + ... + 852896.

It is an arithmetic number, because the mean of its divisors is an integer number (77086800).

Almost surely, 2^1645078761 is an apocalyptic number.

It is an amenable number.

1645078761 is a deficient number, since it is larger than the sum of its proper divisors (821698839).

1645078761 is a wasteful number, since it uses less digits than its factorization.

1645078761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2306 (or 2300 counting only the distinct ones).

The product of its (nonzero) digits is 282240, while the sum is 45.

The square root of 1645078761 is about 40559.5705228741. The cubic root of 1645078761 is about 1180.4897806400.

The spelling of 1645078761 in words is "one billion, six hundred forty-five million, seventy-eight thousand, seven hundred sixty-one".