1864644649 has 4 divisors (see below), whose sum is σ = 2131022464. Its totient is φ = 1598266836.

The previous prime is 1864644623. The next prime is 1864644653. The reversal of 1864644649 is 9464464681.

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: 9464464681 = 7 ⋅1352066383.

It is a cyclic number.

It is not a de Polignac number, because 1864644649 - 2¹³ = 1864636457 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1864644596 and 1864644605.

It is not an unprimeable number, because it can be changed into a prime (1864644619) 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, 133188897 + ... + 133188910.

It is an arithmetic number, because the mean of its divisors is an integer number (532755616).

Almost surely, 2^1864644649 is an apocalyptic number.

It is an amenable number.

1864644649 is a deficient number, since it is larger than the sum of its proper divisors (266377815).

1864644649 is an equidigital number, since it uses as much as digits as its factorization.

1864644649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 266377814.

The product of its digits is 3981312, while the sum is 52.

The square root of 1864644649 is about 43181.5313415354. The cubic root of 1864644649 is about 1230.8317570251.

The spelling of 1864644649 in words is "one billion, eight hundred sixty-four million, six hundred forty-four thousand, six hundred forty-nine".