81311053550 has 48 divisors (see below), whose sum is σ = 162849197520. Its totient is φ = 30092367360.

The previous prime is 81311053547. The next prime is 81311053631. The reversal of 81311053550 is 5535011318.

It is a super-2 number, since 2×81311053550² (a number of 23 digits) contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 760529 + ... + 860828.

It is an arithmetic number, because the mean of its divisors is an integer number (3392691615).

Almost surely, 2^81311053550 is an apocalyptic number.

81311053550 is an abundant number, since it is smaller than the sum of its proper divisors (81538143970).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81311053550 is a wasteful number, since it uses less digits than its factorization.

81311053550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1621445 (or 1621440 counting only the distinct ones).

The product of its (nonzero) digits is 9000, while the sum is 32.

Adding to 81311053550 its reverse (5535011318), we get a palindrome (86846064868).

The spelling of 81311053550 in words is "eighty-one billion, three hundred eleven million, fifty-three thousand, five hundred fifty".