81637706 has 16 divisors (see below), whose sum is σ = 129854016. Its totient is φ = 38360256.

The previous prime is 81637687. The next prime is 81637709. The reversal of 81637706 is 60773618.

It is a self number, because there is not a number n which added to its sum of digits gives 81637706.

It is not an unprimeable number, because it can be changed into a prime (81637709) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28805 + ... + 31511.

It is an arithmetic number, because the mean of its divisors is an integer number (8115876).

Almost surely, 2^81637706 is an apocalyptic number.

81637706 is a deficient number, since it is larger than the sum of its proper divisors (48216310).

81637706 is a wasteful number, since it uses less digits than its factorization.

81637706 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3613.

The product of its (nonzero) digits is 42336, while the sum is 38.

The square root of 81637706 is about 9035.3586536451. The cubic root of 81637706 is about 433.8073748596.

The spelling of 81637706 in words is "eighty-one million, six hundred thirty-seven thousand, seven hundred six".