81511001 has 16 divisors (see below), whose sum is σ = 96018048. Its totient is φ = 68217600.

The previous prime is 81510991. The next prime is 81511021. The reversal of 81511001 is 10011518.

It is a de Polignac number, because none of the positive numbers 2^k-81511001 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81511021) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 92081 + ... + 92961.

It is an arithmetic number, because the mean of its divisors is an integer number (6001128).

Almost surely, 2^81511001 is an apocalyptic number.

It is an amenable number.

81511001 is a deficient number, since it is larger than the sum of its proper divisors (14507047).

81511001 is a wasteful number, since it uses less digits than its factorization.

81511001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1552.

The product of its (nonzero) digits is 40, while the sum is 17.

The square root of 81511001 is about 9028.3443111126. The cubic root of 81511001 is about 433.5828298263.

Adding to 81511001 its reverse (10011518), we get a palindrome (91522519).

The spelling of 81511001 in words is "eighty-one million, five hundred eleven thousand, one".