81035220651 has 16 divisors (see below), whose sum is σ = 134707899648. Its totient is φ = 42096218400.

The previous prime is 81035220599. The next prime is 81035220683. The reversal of 81035220651 is 15602253018.

It is not a de Polignac number, because 81035220651 - 2⁷ = 81035220523 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is not an unprimeable number, because it can be changed into a prime (81035220251) 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, 175400680 + ... + 175401141.

It is an arithmetic number, because the mean of its divisors is an integer number (8419243728).

Almost surely, 2^81035220651 is an apocalyptic number.

81035220651 is a deficient number, since it is larger than the sum of its proper divisors (53672678997).

81035220651 is a wasteful number, since it uses less digits than its factorization.

81035220651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 350801842.

The product of its (nonzero) digits is 14400, while the sum is 33.

Adding to 81035220651 its reverse (15602253018), we get a palindrome (96637473669).

The spelling of 81035220651 in words is "eighty-one billion, thirty-five million, two hundred twenty thousand, six hundred fifty-one".