91977421 has 4 divisors (see below), whose sum is σ = 92528352. Its totient is φ = 91426492.

The previous prime is 91977407. The next prime is 91977443. The reversal of 91977421 is 12477919.

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 91977421 - 2⁹ = 91976909 is a prime.

It is a super-2 number, since 2×91977421² = 16919691947622482, which contains 22 as substring.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91977481) 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, 275215 + ... + 275548.

It is an arithmetic number, because the mean of its divisors is an integer number (23132088).

Almost surely, 2^91977421 is an apocalyptic number.

It is an amenable number.

91977421 is a deficient number, since it is larger than the sum of its proper divisors (550931).

91977421 is a wasteful number, since it uses less digits than its factorization.

91977421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 550930.

The product of its digits is 31752, while the sum is 40.

The square root of 91977421 is about 9590.4859626611. The cubic root of 91977421 is about 451.3988094835.

The spelling of 91977421 in words is "ninety-one million, nine hundred seventy-seven thousand, four hundred twenty-one".