81209213435 has 32 divisors (see below), whose sum is σ = 120433029120. Its totient is φ = 51295514112.

The previous prime is 81209213431. The next prime is 81209213507. The reversal of 81209213435 is 53431290218.

It is a cyclic number.

It is not a de Polignac number, because 81209213435 - 2² = 81209213431 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81209213431) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1424015 + ... + 1479944.

It is an arithmetic number, because the mean of its divisors is an integer number (3763532160).

Almost surely, 2^81209213435 is an apocalyptic number.

81209213435 is a gapful number since it is divisible by the number (85) formed by its first and last digit.

81209213435 is a deficient number, since it is larger than the sum of its proper divisors (39223815685).

81209213435 is a wasteful number, since it uses less digits than its factorization.

81209213435 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2904035.

The product of its (nonzero) digits is 51840, while the sum is 38.

The spelling of 81209213435 in words is "eighty-one billion, two hundred nine million, two hundred thirteen thousand, four hundred thirty-five".