81205510 has 32 divisors (see below), whose sum is σ = 152681760. Its totient is φ = 31057152.

The previous prime is 81205499. The next prime is 81205511. The reversal of 81205510 is 1550218.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81205511) 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, 29722 + ... + 32338.

It is an arithmetic number, because the mean of its divisors is an integer number (4771305).

Almost surely, 2^81205510 is an apocalyptic number.

81205510 is a deficient number, since it is larger than the sum of its proper divisors (71476250).

81205510 is a wasteful number, since it uses less digits than its factorization.

81205510 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2760.

The product of its (nonzero) digits is 400, while the sum is 22.

The square root of 81205510 is about 9011.4099895632. The cubic root of 81205510 is about 433.0404839234.

Adding to 81205510 its reverse (1550218), we get a palindrome (82755728).

The spelling of 81205510 in words is "eighty-one million, two hundred five thousand, five hundred ten".