25640643620542 has 4 divisors (see below), whose sum is σ = 38460965430816. Its totient is φ = 12820321810270.

The previous prime is 25640643620513. The next prime is 25640643620593. The reversal of 25640643620542 is 24502634604652.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6410160905134 + ... + 6410160905137.

It is an arithmetic number, because the mean of its divisors is an integer number (9615241357704).

Almost surely, 2^{25640643620542} is an apocalyptic number.

25640643620542 is a deficient number, since it is larger than the sum of its proper divisors (12820321810274).

25640643620542 is a wasteful number, since it uses less digits than its factorization.

25640643620542 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12820321810273.

The product of its (nonzero) digits is 8294400, while the sum is 49.

The spelling of 25640643620542 in words is "twenty-five trillion, six hundred forty billion, six hundred forty-three million, six hundred twenty thousand, five hundred forty-two".