91787818420 has 12 divisors (see below), whose sum is σ = 192754418724. Its totient is φ = 36715127360.

The previous prime is 91787818411. The next prime is 91787818457. The reversal of 91787818420 is 2481878719.

It can be written as a sum of positive squares in 2 ways, for example, as 23356397584 + 68431420836 = 152828^2 + 261594^2 .

It is a super-2 number, since 2×91787818420² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2294695441 + ... + 2294695480.

It is an arithmetic number, because the mean of its divisors is an integer number (16062868227).

Almost surely, 2^91787818420 is an apocalyptic number.

It is an amenable number.

91787818420 is an abundant number, since it is smaller than the sum of its proper divisors (100966600304).

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

91787818420 is a wasteful number, since it uses less digits than its factorization.

91787818420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4589390930 (or 4589390928 counting only the distinct ones).

The product of its (nonzero) digits is 1806336, while the sum is 55.

The spelling of 91787818420 in words is "ninety-one billion, seven hundred eighty-seven million, eight hundred eighteen thousand, four hundred twenty".