81961453578 has 32 divisors (see below), whose sum is σ = 164891492352. Its totient is φ = 27159246000.

The previous prime is 81961453573. The next prime is 81961453591. The reversal of 81961453578 is 87535416918.

It is not an unprimeable number, because it can be changed into a prime (81961453573) 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, 1745103 + ... + 1791453.

It is an arithmetic number, because the mean of its divisors is an integer number (5152859136).

Almost surely, 2^81961453578 is an apocalyptic number.

81961453578 is an abundant number, since it is smaller than the sum of its proper divisors (82930038774).

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

81961453578 is a wasteful number, since it uses less digits than its factorization.

81961453578 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48090.

The product of its digits is 7257600, while the sum is 57.

The spelling of 81961453578 in words is "eighty-one billion, nine hundred sixty-one million, four hundred fifty-three thousand, five hundred seventy-eight".