91440921664 has 21 divisors (see below), whose sum is σ = 181457879527. Its totient is φ = 45719251264.

The previous prime is 91440921629. The next prime is 91440921673. The reversal of 91440921664 is 46612904419.

The square root of 91440921664 is 302392.

It is a perfect power (a square), and thus also a powerful number.

It is a super-2 number, since 2×91440921664² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 2400237 + ... + 2438035.

Almost surely, 2^91440921664 is an apocalyptic number.

91440921664 is the 302392-nd square number.

It is an amenable number.

91440921664 is a deficient number, since it is larger than the sum of its proper divisors (90016957863).

91440921664 is an frugal number, since it uses more digits than its factorization.

91440921664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 75610 (or 37801 counting only the distinct ones).

The product of its (nonzero) digits is 373248, while the sum is 46.

The spelling of 91440921664 in words is "ninety-one billion, four hundred forty million, nine hundred twenty-one thousand, six hundred sixty-four".