81961753 has 4 divisors (see below), whose sum is σ = 82949328. Its totient is φ = 80974180.

The previous prime is 81961727. The next prime is 81961783. The reversal of 81961753 is 35716918.

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 81961753 - 2¹⁷ = 81830681 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81961723) 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, 493663 + ... + 493828.

It is an arithmetic number, because the mean of its divisors is an integer number (20737332).

Almost surely, 2^81961753 is an apocalyptic number.

81961753 is a gapful number since it is divisible by the number (83) formed by its first and last digit.

It is an amenable number.

81961753 is a deficient number, since it is larger than the sum of its proper divisors (987575).

81961753 is an equidigital number, since it uses as much as digits as its factorization.

81961753 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 987574.

The product of its digits is 45360, while the sum is 40.

The square root of 81961753 is about 9053.2730545367. The cubic root of 81961753 is about 434.3805919816.

The spelling of 81961753 in words is "eighty-one million, nine hundred sixty-one thousand, seven hundred fifty-three".