91439949821 has 16 divisors (see below), whose sum is σ = 99903643008. Its totient is φ = 83001542400.

The previous prime is 91439949767. The next prime is 91439949829. The reversal of 91439949821 is 12894993419.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-91439949821 is a prime.

It is a super-2 number, since 2×91439949821² (a number of 23 digits) 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 (91439949829) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 36270041 + ... + 36272561.

It is an arithmetic number, because the mean of its divisors is an integer number (6243977688).

Almost surely, 2^91439949821 is an apocalyptic number.

It is an amenable number.

91439949821 is a deficient number, since it is larger than the sum of its proper divisors (8463693187).

91439949821 is a wasteful number, since it uses less digits than its factorization.

91439949821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6212.

The product of its digits is 5038848, while the sum is 59.

The spelling of 91439949821 in words is "ninety-one billion, four hundred thirty-nine million, nine hundred forty-nine thousand, eight hundred twenty-one".