1648743581 has 4 divisors (see below), whose sum is σ = 1655012832. Its totient is φ = 1642474332.

The previous prime is 1648743517. The next prime is 1648743637. The reversal of 1648743581 is 1853478461.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1853478461 = 1019 ⋅1818919.

It is a cyclic number.

It is not a de Polignac number, because 1648743581 - 2⁶ = 1648743517 is a prime.

It is a super-2 number, since 2×1648743581² = 5436710791777407122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1648743511) 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, 3134231 + ... + 3134756.

It is an arithmetic number, because the mean of its divisors is an integer number (413753208).

Almost surely, 2^1648743581 is an apocalyptic number.

It is an amenable number.

1648743581 is a deficient number, since it is larger than the sum of its proper divisors (6269251).

1648743581 is an equidigital number, since it uses as much as digits as its factorization.

1648743581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6269250.

The product of its digits is 645120, while the sum is 47.

The square root of 1648743581 is about 40604.7236291543. The cubic root of 1648743581 is about 1181.3657415177.

The spelling of 1648743581 in words is "one billion, six hundred forty-eight million, seven hundred forty-three thousand, five hundred eighty-one".