25721161701666 has 16 divisors (see below), whose sum is σ = 51444977080224. Its totient is φ = 8573278287744.

The previous prime is 25721161701647. The next prime is 25721161701667. The reversal of 25721161701666 is 66610716112752.

It is not an unprimeable number, because it can be changed into a prime (25721161701667) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 110443855 + ... + 110676498.

It is an arithmetic number, because the mean of its divisors is an integer number (3215311067514).

Almost surely, 2^{25721161701666} is an apocalyptic number.

25721161701666 is an abundant number, since it is smaller than the sum of its proper divisors (25723815378558).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

25721161701666 is a wasteful number, since it uses less digits than its factorization.

25721161701666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 221139745.

The product of its (nonzero) digits is 1270080, while the sum is 51.

The spelling of 25721161701666 in words is "twenty-five trillion, seven hundred twenty-one billion, one hundred sixty-one million, seven hundred one thousand, six hundred sixty-six".