81619569405 has 160 divisors (see below), whose sum is σ = 164656800000. Its totient is φ = 38336025600.

The previous prime is 81619569377. The next prime is 81619569407. The reversal of 81619569405 is 50496591618.

It is not a de Polignac number, because 81619569405 - 2⁶ = 81619569341 is a prime.

It is a super-2 number, since 2×81619569405² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81619569407) by changing a digit.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 27214096 + ... + 27217094.

It is an arithmetic number, because the mean of its divisors is an integer number (1029105000).

Almost surely, 2^81619569405 is an apocalyptic number.

It is an amenable number.

81619569405 is an abundant number, since it is smaller than the sum of its proper divisors (83037230595).

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

81619569405 is a wasteful number, since it uses less digits than its factorization.

81619569405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3217 (or 3208 counting only the distinct ones).

The product of its (nonzero) digits is 2332800, while the sum is 54.

The spelling of 81619569405 in words is "eighty-one billion, six hundred nineteen million, five hundred sixty-nine thousand, four hundred five".