21661465725747 has 40 divisors (see below), whose sum is σ = 32504959000800. Its totient is φ = 14375637959040.

The previous prime is 21661465725727. The next prime is 21661465725751. The reversal of 21661465725747 is 74752756416612.

21661465725747 is a `hidden beast` number, since 2 + 1 + 6 + 6 + 1 + 4 + 6 + 57 + 2 + 574 + 7 = 666.

It is not a de Polignac number, because 21661465725747 - 2¹⁴ = 21661465709363 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21661465725727) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 81946722 + ... + 82210632.

It is an arithmetic number, because the mean of its divisors is an integer number (812623975020).

Almost surely, 2^{21661465725747} is an apocalyptic number.

21661465725747 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

21661465725747 is a deficient number, since it is larger than the sum of its proper divisors (10843493275053).

21661465725747 is a wasteful number, since it uses less digits than its factorization.

21661465725747 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 268505 (or 268496 counting only the distinct ones).

The product of its digits is 118540800, while the sum is 63.

The spelling of 21661465725747 in words is "twenty-one trillion, six hundred sixty-one billion, four hundred sixty-five million, seven hundred twenty-five thousand, seven hundred forty-seven".