81421252545 has 16 divisors (see below), whose sum is σ = 130295692800. Its totient is φ = 43417438464.

The previous prime is 81421252519. The next prime is 81421252547. The reversal of 81421252545 is 54525212418.

It is not a de Polignac number, because 81421252545 - 2⁶ = 81421252481 is a prime.

It is a super-3 number, since 3×81421252545³ (a number of 34 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (81421252547) 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, 358120 + ... + 539529.

It is an arithmetic number, because the mean of its divisors is an integer number (8143480800).

Almost surely, 2^81421252545 is an apocalyptic number.

It is an amenable number.

81421252545 is a deficient number, since it is larger than the sum of its proper divisors (48874440255).

81421252545 is a wasteful number, since it uses less digits than its factorization.

81421252545 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 903704.

The product of its digits is 128000, while the sum is 39.

The spelling of 81421252545 in words is "eighty-one billion, four hundred twenty-one million, two hundred fifty-two thousand, five hundred forty-five".