81643430 has 16 divisors (see below), whose sum is σ = 160318224. Its totient is φ = 29688480.

The previous prime is 81643427. The next prime is 81643459. The reversal of 81643430 is 3434618.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 81643393 and 81643402.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 370997 + ... + 371216.

It is an arithmetic number, because the mean of its divisors is an integer number (10019889).

Almost surely, 2^81643430 is an apocalyptic number.

81643430 is a deficient number, since it is larger than the sum of its proper divisors (78674794).

81643430 is a wasteful number, since it uses less digits than its factorization.

81643430 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 742231.

The product of its (nonzero) digits is 6912, while the sum is 29.

The square root of 81643430 is about 9035.6754036431. The cubic root of 81643430 is about 433.8175133748.

The spelling of 81643430 in words is "eighty-one million, six hundred forty-three thousand, four hundred thirty".