81209213436 has 48 divisors (see below), whose sum is σ = 204090003488. Its totient is φ = 24984288000.

The previous prime is 81209213431. The next prime is 81209213507. The reversal of 81209213436 is 63431290218.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a junction number, because it is equal to n+sod(n) for n = 81209213394 and 81209213403.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81209213431) 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, 1403886 + ... + 1460586.

Almost surely, 2^81209213436 is an apocalyptic number.

It is an amenable number.

81209213436 is an abundant number, since it is smaller than the sum of its proper divisors (122880790052).

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

81209213436 is a wasteful number, since it uses less digits than its factorization.

81209213436 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65902 (or 65900 counting only the distinct ones).

The product of its (nonzero) digits is 62208, while the sum is 39.

It can be divided in two parts, 812092 and 13436, that added together give a palindrome (825528).

The spelling of 81209213436 in words is "eighty-one billion, two hundred nine million, two hundred thirteen thousand, four hundred thirty-six".