81473657501 has 4 divisors (see below), whose sum is σ = 81630037404. Its totient is φ = 81317277600.

The previous prime is 81473657471. The next prime is 81473657533. The reversal of 81473657501 is 10575637418.

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 62187391876 + 19286265625 = 249374^2 + 138875^2 .

It is a cyclic number.

It is not a de Polignac number, because 81473657501 - 2⁶ = 81473657437 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 (81473657101) 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, 78189170 + ... + 78190211.

It is an arithmetic number, because the mean of its divisors is an integer number (20407509351).

Almost surely, 2^81473657501 is an apocalyptic number.

It is an amenable number.

81473657501 is a deficient number, since it is larger than the sum of its proper divisors (156379903).

81473657501 is a wasteful number, since it uses less digits than its factorization.

81473657501 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 156379902.

The product of its (nonzero) digits is 705600, while the sum is 47.

The spelling of 81473657501 in words is "eighty-one billion, four hundred seventy-three million, six hundred fifty-seven thousand, five hundred one".