81006290668442 has 4 divisors (see below), whose sum is σ = 121509436002666. Its totient is φ = 40503145334220.

The previous prime is 81006290668417. The next prime is 81006290668453. The reversal of 81006290668442 is 24486609260018.

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., 42280698574321 + 38725592094121 = 6502361^2 + 6222989^2 .

It is a super-2 number, since 2×81006290668442² (a number of 29 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20251572667109 + ... + 20251572667112.

Almost surely, 2^{81006290668442} is an apocalyptic number.

81006290668442 is a deficient number, since it is larger than the sum of its proper divisors (40503145334224).

81006290668442 is a wasteful number, since it uses less digits than its factorization.

81006290668442 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40503145334223.

The product of its (nonzero) digits is 7962624, while the sum is 56.

The spelling of 81006290668442 in words is "eighty-one trillion, six billion, two hundred ninety million, six hundred sixty-eight thousand, four hundred forty-two".