81780938541 has 12 divisors (see below), whose sum is σ = 119891128032. Its totient is φ = 53706884616.

The previous prime is 81780938507. The next prime is 81780938549. The reversal of 81780938541 is 14583908718.

81780938541 is a `hidden beast` number, since 8 + 1 + 7 + 8 + 0 + 93 + 8 + 541 = 666.

It is not a de Polignac number, because 81780938541 - 2¹⁰ = 81780937517 is a prime.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81780938549) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 67811121 + ... + 67812326.

It is an arithmetic number, because the mean of its divisors is an integer number (9990927336).

Almost surely, 2^81780938541 is an apocalyptic number.

It is an amenable number.

81780938541 is a deficient number, since it is larger than the sum of its proper divisors (38110189491).

81780938541 is a wasteful number, since it uses less digits than its factorization.

81780938541 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 135623520 (or 135623517 counting only the distinct ones).

The product of its (nonzero) digits is 1935360, while the sum is 54.

The spelling of 81780938541 in words is "eighty-one billion, seven hundred eighty million, nine hundred thirty-eight thousand, five hundred forty-one".