81438770738053 has 4 divisors (see below), whose sum is σ = 82245095200908. Its totient is φ = 80632446275200.

The previous prime is 81438770738021. The next prime is 81438770738137. The reversal of 81438770738053 is 35083707783418.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 48253820571009 + 33184950167044 = 6946497^2 + 5760638^2 .

It is a cyclic number.

It is not a de Polignac number, because 81438770738053 - 2⁵ = 81438770738021 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81438770735053) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 403162231276 + ... + 403162231477.

It is an arithmetic number, because the mean of its divisors is an integer number (20561273800227).

Almost surely, 2^{81438770738053} is an apocalyptic number.

It is an amenable number.

81438770738053 is a deficient number, since it is larger than the sum of its proper divisors (806324462855).

81438770738053 is a wasteful number, since it uses less digits than its factorization.

81438770738053 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 806324462854.

The product of its (nonzero) digits is 94832640, while the sum is 64.

The spelling of 81438770738053 in words is "eighty-one trillion, four hundred thirty-eight billion, seven hundred seventy million, seven hundred thirty-eight thousand, fifty-three".