1645283781 has 24 divisors (see below), whose sum is σ = 2414295936. Its totient is φ = 1079477280.

The previous prime is 1645283753. The next prime is 1645283791. The reversal of 1645283781 is 1873825461.

1645283781 is a `hidden beast` number, since 16 + 4 + 528 + 37 + 81 = 666.

It is not a de Polignac number, because 1645283781 - 2¹¹ = 1645281733 is a prime.

It is a super-2 number, since 2×1645283781² = 5413917440043311922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1645283791) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 415296 + ... + 419238.

It is an arithmetic number, because the mean of its divisors is an integer number (100595664).

Almost surely, 2^1645283781 is an apocalyptic number.

It is an amenable number.

1645283781 is a deficient number, since it is larger than the sum of its proper divisors (769012155).

1645283781 is a wasteful number, since it uses less digits than its factorization.

1645283781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4673 (or 4670 counting only the distinct ones).

The product of its digits is 322560, while the sum is 45.

The square root of 1645283781 is about 40562.0978377598. The cubic root of 1645283781 is about 1180.5388186085.

The spelling of 1645283781 in words is "one billion, six hundred forty-five million, two hundred eighty-three thousand, seven hundred eighty-one".