81732232921 has 2 divisors, whose sum is σ = 81732232922. Its totient is φ = 81732232920.

The previous prime is 81732232877. The next prime is 81732232951. The reversal of 81732232921 is 12923223718.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 80304224400 + 1428008521 = 283380^2 + 37789^2 .

It is a cyclic number.

It is not a de Polignac number, because 81732232921 - 2¹⁵ = 81732200153 is a prime.

It is not a weakly prime, because it can be changed into another prime (81732232951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40866116460 + 40866116461.

It is an arithmetic number, because the mean of its divisors is an integer number (40866116461).

Almost surely, 2^81732232921 is an apocalyptic number.

It is an amenable number.

81732232921 is a deficient number, since it is larger than the sum of its proper divisors (1).

81732232921 is an equidigital number, since it uses as much as digits as its factorization.

81732232921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 72576, while the sum is 40.

The spelling of 81732232921 in words is "eighty-one billion, seven hundred thirty-two million, two hundred thirty-two thousand, nine hundred twenty-one".