201381866721 has 24 divisors (see below), whose sum is σ = 334866489984. Its totient is φ = 114235381440.

The previous prime is 201381866717. The next prime is 201381866753. The reversal of 201381866721 is 127668183102.

201381866721 is a `hidden beast` number, since 201 + 381 + 8 + 6 + 67 + 2 + 1 = 666.

It is not a de Polignac number, because 201381866721 - 2² = 201381866717 is a prime.

It is not an unprimeable number, because it can be changed into a prime (201381866321) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 11657565 + ... + 11674826.

It is an arithmetic number, because the mean of its divisors is an integer number (13952770416).

Almost surely, 2^201381866721 is an apocalyptic number.

201381866721 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

201381866721 is a deficient number, since it is larger than the sum of its proper divisors (133484623263).

201381866721 is a wasteful number, since it uses less digits than its factorization.

201381866721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23332541 (or 23332538 counting only the distinct ones).

The product of its (nonzero) digits is 193536, while the sum is 45.

The spelling of 201381866721 in words is "two hundred one billion, three hundred eighty-one million, eight hundred sixty-six thousand, seven hundred twenty-one".