81213526 has 4 divisors (see below), whose sum is σ = 121820292. Its totient is φ = 40606762.

The previous prime is 81213523. The next prime is 81213527. The reversal of 81213526 is 62531218.

It is a semiprime because it is the product of two primes.

It is a junction number, because it is equal to n+sod(n) for n = 81213494 and 81213503.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81213523) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20303380 + ... + 20303383.

It is an arithmetic number, because the mean of its divisors is an integer number (30455073).

Almost surely, 2^81213526 is an apocalyptic number.

81213526 is a deficient number, since it is larger than the sum of its proper divisors (40606766).

81213526 is a wasteful number, since it uses less digits than its factorization.

81213526 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40606765.

The product of its digits is 2880, while the sum is 28.

The square root of 81213526 is about 9011.8547480527. The cubic root of 81213526 is about 433.0547322928.

The spelling of 81213526 in words is "eighty-one million, two hundred thirteen thousand, five hundred twenty-six".