91421730 has 128 divisors (see below), whose sum is σ = 261273600. Its totient is φ = 22680000.

The previous prime is 91421719. The next prime is 91421731. The reversal of 91421730 is 3712419.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a junction number, because it is equal to n+sod(n) for n = 91421694 and 91421703.

It is not an unprimeable number, because it can be changed into a prime (91421731) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 364105 + ... + 364355.

It is an arithmetic number, because the mean of its divisors is an integer number (2041200).

Almost surely, 2^91421730 is an apocalyptic number.

91421730 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 91421730, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (130636800).

91421730 is an abundant number, since it is smaller than the sum of its proper divisors (169851870).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

91421730 is a wasteful number, since it uses less digits than its factorization.

91421730 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 357 (or 351 counting only the distinct ones).

The product of its (nonzero) digits is 1512, while the sum is 27.

The square root of 91421730 is about 9561.4711211194. The cubic root of 91421730 is about 450.4879152282.

It can be divided in two parts, 91 and 421730, that added together give a triangular number (421821 = T₉₁₈).

The spelling of 91421730 in words is "ninety-one million, four hundred twenty-one thousand, seven hundred thirty".