81421979753 has 4 divisors (see below), whose sum is σ = 81422697600. Its totient is φ = 81421261908.

The previous prime is 81421979729. The next prime is 81421979761. The reversal of 81421979753 is 35797912418.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 81421979753 - 2¹⁸ = 81421717609 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81421979713) 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, 147125 + ... + 429522.

It is an arithmetic number, because the mean of its divisors is an integer number (20355674400).

Almost surely, 2^81421979753 is an apocalyptic number.

It is an amenable number.

81421979753 is a deficient number, since it is larger than the sum of its proper divisors (717847).

81421979753 is a wasteful number, since it uses less digits than its factorization.

81421979753 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 717846.

The product of its digits is 3810240, while the sum is 56.

The spelling of 81421979753 in words is "eighty-one billion, four hundred twenty-one million, nine hundred seventy-nine thousand, seven hundred fifty-three".