81551366 has 16 divisors (see below), whose sum is σ = 133544544. Its totient is φ = 37122624.

The previous prime is 81551357. The next prime is 81551387. The reversal of 81551366 is 66315518.

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, 19586 + ... + 23381.

It is an arithmetic number, because the mean of its divisors is an integer number (8346534).

Almost surely, 2^81551366 is an apocalyptic number.

81551366 is a deficient number, since it is larger than the sum of its proper divisors (51993178).

81551366 is a wasteful number, since it uses less digits than its factorization.

81551366 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43055.

The product of its digits is 21600, while the sum is 35.

The square root of 81551366 is about 9030.5794941410. The cubic root of 81551366 is about 433.6543894217.

The spelling of 81551366 in words is "eighty-one million, five hundred fifty-one thousand, three hundred sixty-six".