81562219281 has 27 divisors (see below), whose sum is σ = 123186829129. Its totient is φ = 51998124552.

The previous prime is 81562219267. The next prime is 81562219283. The reversal of 81562219281 is 18291226518.

The square root of 81562219281 is 285591.

It is a perfect power (a square), and thus also a powerful number.

81562219281 is a `hidden beast` number, since 8 + 1 + 5 + 622 + 19 + 2 + 8 + 1 = 666.

It is not a de Polignac number, because 81562219281 - 2¹⁵ = 81562186513 is a prime.

It is a super-2 number, since 2×81562219281² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81562219283) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 19703710 + ... + 19707848.

Almost surely, 2^81562219281 is an apocalyptic number.

81562219281 is the 285591-st square number.

81562219281 is the 142796-th centered octagonal number.

It is an amenable number.

81562219281 is a deficient number, since it is larger than the sum of its proper divisors (41624609848).

81562219281 is an frugal number, since it uses more digits than its factorization.

81562219281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8330 (or 4165 counting only the distinct ones).

The product of its digits is 138240, while the sum is 45.

The spelling of 81562219281 in words is "eighty-one billion, five hundred sixty-two million, two hundred nineteen thousand, two hundred eighty-one".