81333900749 has 4 divisors (see below), whose sum is σ = 81342160320. Its totient is φ = 81325641180.

The previous prime is 81333900629. The next prime is 81333900779. The reversal of 81333900749 is 94700933318.

It is a happy number.

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.

It is a cyclic number.

It is not a de Polignac number, because 81333900749 - 2¹² = 81333896653 is a prime.

It is a super-2 number, since 2×81333900749² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81333900779) 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, 4114997 + ... + 4134714.

It is an arithmetic number, because the mean of its divisors is an integer number (20335540080).

Almost surely, 2^81333900749 is an apocalyptic number.

It is an amenable number.

81333900749 is a deficient number, since it is larger than the sum of its proper divisors (8259571).

81333900749 is an equidigital number, since it uses as much as digits as its factorization.

81333900749 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8259570.

The product of its (nonzero) digits is 489888, while the sum is 47.

The spelling of 81333900749 in words is "eighty-one billion, three hundred thirty-three million, nine hundred thousand, seven hundred forty-nine".