81547435397 has 4 divisors (see below), whose sum is σ = 81557413920. Its totient is φ = 81537456876.

The previous prime is 81547435373. The next prime is 81547435427. The reversal of 81547435397 is 79353474518.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81547435397 - 2⁸ = 81547435141 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81547435897) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4976993 + ... + 4993350.

It is an arithmetic number, because the mean of its divisors is an integer number (20389353480).

Almost surely, 2^81547435397 is an apocalyptic number.

It is an amenable number.

81547435397 is a deficient number, since it is larger than the sum of its proper divisors (9978523).

81547435397 is an equidigital number, since it uses as much as digits as its factorization.

81547435397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9978522.

The product of its digits is 12700800, while the sum is 56.

The spelling of 81547435397 in words is "eighty-one billion, five hundred forty-seven million, four hundred thirty-five thousand, three hundred ninety-seven".