91821261 has 8 divisors (see below), whose sum is σ = 139918144. Its totient is φ = 52469280.

The previous prime is 91821259. The next prime is 91821271. The reversal of 91821261 is 16212819.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 91821261 - 2¹ = 91821259 is a prime.

It is a super-2 number, since 2×91821261² = 16862287943260242, which 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 (91821271) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2186200 + ... + 2186241.

It is an arithmetic number, because the mean of its divisors is an integer number (17489768).

Almost surely, 2^91821261 is an apocalyptic number.

It is an amenable number.

91821261 is a deficient number, since it is larger than the sum of its proper divisors (48096883).

91821261 is a wasteful number, since it uses less digits than its factorization.

91821261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4372451.

The product of its digits is 1728, while the sum is 30.

The square root of 91821261 is about 9582.3411022568. The cubic root of 91821261 is about 451.1432019367.

The spelling of 91821261 in words is "ninety-one million, eight hundred twenty-one thousand, two hundred sixty-one".