25643646439 has 4 divisors (see below), whose sum is σ = 25777906560. Its totient is φ = 25509386320.

The previous prime is 25643646409. The next prime is 25643646463. The reversal of 25643646439 is 93464634652.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-25643646439 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 (25643646409) 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, 67129774 + ... + 67130155.

It is an arithmetic number, because the mean of its divisors is an integer number (6444476640).

Almost surely, 2^25643646439 is an apocalyptic number.

25643646439 is a deficient number, since it is larger than the sum of its proper divisors (134260121).

25643646439 is a wasteful number, since it uses less digits than its factorization.

25643646439 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 134260120.

The product of its digits is 11197440, while the sum is 52.

The spelling of 25643646439 in words is "twenty-five billion, six hundred forty-three million, six hundred forty-six thousand, four hundred thirty-nine".