81511258 has 4 divisors (see below), whose sum is σ = 122266890. Its totient is φ = 40755628.

The previous prime is 81511249. The next prime is 81511271. The reversal of 81511258 is 85211518.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 70107129 + 11404129 = 8373^2 + 3377^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20377813 + ... + 20377816.

Almost surely, 2^81511258 is an apocalyptic number.

81511258 is a deficient number, since it is larger than the sum of its proper divisors (40755632).

81511258 is a wasteful number, since it uses less digits than its factorization.

81511258 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40755631.

The product of its digits is 3200, while the sum is 31.

The square root of 81511258 is about 9028.3585440544. The cubic root of 81511258 is about 433.5832855140.

It can be divided in two parts, 8151 and 1258, that added together give a square (9409 = 97²).

The spelling of 81511258 in words is "eighty-one million, five hundred eleven thousand, two hundred fifty-eight".