81228990049 has 3 divisors (see below), whose sum is σ = 81229275057. Its totient is φ = 81228705042.

The previous prime is 81228990041. The next prime is 81228990061. The reversal of 81228990049 is 94009982218.

The square root of 81228990049 is 285007.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 81228990049 - 2³ = 81228990041 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81228989978 and 81228990005.

It is not an unprimeable number, because it can be changed into a prime (81228990041) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 142504 + ... + 427510.

It is an arithmetic number, because the mean of its divisors is an integer number (27076425019).

Almost surely, 2^81228990049 is an apocalyptic number.

81228990049 is the 285007-th square number.

81228990049 is the 142504-th centered octagonal number.

It is an amenable number.

81228990049 is a deficient number, since it is larger than the sum of its proper divisors (285008).

81228990049 is an frugal number, since it uses more digits than its factorization.

81228990049 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 570014 (or 285007 counting only the distinct ones).

The product of its (nonzero) digits is 746496, while the sum is 52.

The spelling of 81228990049 in words is "eighty-one billion, two hundred twenty-eight million, nine hundred ninety thousand, forty-nine".