81640363550 has 48 divisors (see below), whose sum is σ = 157643191440. Its totient is φ = 31418499840.

The previous prime is 81640363489. The next prime is 81640363589. The reversal of 81640363550 is 5536304618.

It is a junction number, because it is equal to n+sod(n) for n = 81640363498 and 81640363507.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 310874 + ... + 509826.

It is an arithmetic number, because the mean of its divisors is an integer number (3284233155).

Almost surely, 2^81640363550 is an apocalyptic number.

81640363550 is a deficient number, since it is larger than the sum of its proper divisors (76002827890).

81640363550 is a wasteful number, since it uses less digits than its factorization.

81640363550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 199277 (or 199272 counting only the distinct ones).

The product of its (nonzero) digits is 259200, while the sum is 41.

The spelling of 81640363550 in words is "eighty-one billion, six hundred forty million, three hundred sixty-three thousand, five hundred fifty".