1643205253 has 16 divisors (see below), whose sum is σ = 1756641600. Its totient is φ = 1532545920.

The previous prime is 1643205233. The next prime is 1643205271. The reversal of 1643205253 is 3525023461.

It is a happy number.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1643205253 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 (1643205233) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1304538 + ... + 1305796.

It is an arithmetic number, because the mean of its divisors is an integer number (109790100).

Almost surely, 2^1643205253 is an apocalyptic number.

It is an amenable number.

1643205253 is a deficient number, since it is larger than the sum of its proper divisors (113436347).

1643205253 is a wasteful number, since it uses less digits than its factorization.

1643205253 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2292.

The product of its (nonzero) digits is 21600, while the sum is 31.

The square root of 1643205253 is about 40536.4681860667. The cubic root of 1643205253 is about 1180.0414744113.

The spelling of 1643205253 in words is "one billion, six hundred forty-three million, two hundred five thousand, two hundred fifty-three".