1640513261 has 4 divisors (see below), whose sum is σ = 1640685024. Its totient is φ = 1640341500.

The previous prime is 1640513227. The next prime is 1640513297. The reversal of 1640513261 is 1623150461.

It is a happy number.

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.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1640513261 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1640513221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 70655 + ... + 90956.

It is an arithmetic number, because the mean of its divisors is an integer number (410171256).

Almost surely, 2^1640513261 is an apocalyptic number.

It is an amenable number.

1640513261 is a deficient number, since it is larger than the sum of its proper divisors (171763).

1640513261 is a wasteful number, since it uses less digits than its factorization.

1640513261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 171762.

The product of its (nonzero) digits is 4320, while the sum is 29.

The square root of 1640513261 is about 40503.2500054008. The cubic root of 1640513261 is about 1179.3967185775.

The spelling of 1640513261 in words is "one billion, six hundred forty million, five hundred thirteen thousand, two hundred sixty-one".