81649635 has 16 divisors (see below), whose sum is σ = 131328000. Its totient is φ = 43316960.

The previous prime is 81649621. The next prime is 81649637. The reversal of 81649635 is 53694618.

It is not a de Polignac number, because 81649635 - 2⁶ = 81649571 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81649637) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11385 + ... + 17114.

It is an arithmetic number, because the mean of its divisors is an integer number (8208000).

Almost surely, 2^81649635 is an apocalyptic number.

81649635 is a deficient number, since it is larger than the sum of its proper divisors (49678365).

81649635 is a wasteful number, since it uses less digits than its factorization.

81649635 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28698.

The product of its digits is 155520, while the sum is 42.

The square root of 81649635 is about 9036.0187582807. The cubic root of 81649635 is about 433.8285033160.

The spelling of 81649635 in words is "eighty-one million, six hundred forty-nine thousand, six hundred thirty-five".