81520335 has 48 divisors (see below), whose sum is σ = 152993568. Its totient is φ = 39916800.

The previous prime is 81520333. The next prime is 81520367. The reversal of 81520335 is 53302518.

It is not a de Polignac number, because 81520335 - 2¹ = 81520333 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81520299 and 81520308.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81520331) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 193425 + ... + 193845.

It is an arithmetic number, because the mean of its divisors is an integer number (3187366).

Almost surely, 2^81520335 is an apocalyptic number.

81520335 is a deficient number, since it is larger than the sum of its proper divisors (71473233).

81520335 is a wasteful number, since it uses less digits than its factorization.

81520335 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 776 (or 773 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 27.

The square root of 81520335 is about 9028.8612238754. The cubic root of 81520335 is about 433.5993793620.

The spelling of 81520335 in words is "eighty-one million, five hundred twenty thousand, three hundred thirty-five".