91978541 has 4 divisors (see below), whose sum is σ = 95977632. Its totient is φ = 87979452.

The previous prime is 91978529. The next prime is 91978543. The reversal of 91978541 is 14587919.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 91978541 - 2¹⁰ = 91977517 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 91978492 and 91978501.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91978543) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1999511 + ... + 1999556.

It is an arithmetic number, because the mean of its divisors is an integer number (23994408).

Almost surely, 2^91978541 is an apocalyptic number.

It is an amenable number.

91978541 is a deficient number, since it is larger than the sum of its proper divisors (3999091).

91978541 is a wasteful number, since it uses less digits than its factorization.

91978541 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3999090.

The product of its digits is 90720, while the sum is 44.

The square root of 91978541 is about 9590.5443536850. The cubic root of 91978541 is about 451.4006416890.

The spelling of 91978541 in words is "ninety-one million, nine hundred seventy-eight thousand, five hundred forty-one".