81643510 has 32 divisors (see below), whose sum is σ = 158669280. Its totient is φ = 30067968.

The previous prime is 81643481. The next prime is 81643543. The reversal of 81643510 is 1534618.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 85194 + ... + 86146.

It is an arithmetic number, because the mean of its divisors is an integer number (4958415).

Almost surely, 2^81643510 is an apocalyptic number.

81643510 is a deficient number, since it is larger than the sum of its proper divisors (77025770).

81643510 is a wasteful number, since it uses less digits than its factorization.

81643510 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1632.

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

The square root of 81643510 is about 9035.6798305385. The cubic root of 81643510 is about 433.8176550698.

The spelling of 81643510 in words is "eighty-one million, six hundred forty-three thousand, five hundred ten".