1640634213 has 4 divisors (see below), whose sum is σ = 2187512288. Its totient is φ = 1093756140.

The previous prime is 1640634209. The next prime is 1640634221. The reversal of 1640634213 is 3124360461.

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: 3124360461 = 3 ⋅1041453487.

It is not a de Polignac number, because 1640634213 - 2² = 1640634209 is a prime.

It is a super-2 number, since 2×1640634213² = 5383361241732258738, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1640634013) 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, 273439033 + ... + 273439038.

It is an arithmetic number, because the mean of its divisors is an integer number (546878072).

Almost surely, 2^1640634213 is an apocalyptic number.

It is an amenable number.

1640634213 is a deficient number, since it is larger than the sum of its proper divisors (546878075).

1640634213 is an equidigital number, since it uses as much as digits as its factorization.

1640634213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 546878074.

The product of its (nonzero) digits is 10368, while the sum is 30.

The square root of 1640634213 is about 40504.7430926305. The cubic root of 1640634213 is about 1179.4257027761.

Adding to 1640634213 its reverse (3124360461), we get a palindrome (4764994674).

The spelling of 1640634213 in words is "one billion, six hundred forty million, six hundred thirty-four thousand, two hundred thirteen".