1921217640181 has 24 divisors (see below), whose sum is σ = 2346908843520. Its totient is φ = 1565126795232.

The previous prime is 1921217640179. The next prime is 1921217640191. The reversal of 1921217640181 is 1810467121291.

It is not a de Polignac number, because 1921217640181 - 2¹ = 1921217640179 is a prime.

It is a super-2 number, since 2×1921217640181² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1921217640101) 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, 5252101 + ... + 5605978.

It is an arithmetic number, because the mean of its divisors is an integer number (97787868480).

Almost surely, 2^{1921217640181} is an apocalyptic number.

It is an amenable number.

1921217640181 is a deficient number, since it is larger than the sum of its proper divisors (425691203339).

1921217640181 is a wasteful number, since it uses less digits than its factorization.

1921217640181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10858273 (or 10858266 counting only the distinct ones).

The product of its (nonzero) digits is 48384, while the sum is 43.

The spelling of 1921217640181 in words is "one trillion, nine hundred twenty-one billion, two hundred seventeen million, six hundred forty thousand, one hundred eighty-one".