81221963 has 2 divisors, whose sum is σ = 81221964. Its totient is φ = 81221962.

The previous prime is 81221951. The next prime is 81221983. The reversal of 81221963 is 36912218.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81221963 - 2¹⁰ = 81220939 is a prime.

It is not a weakly prime, because it can be changed into another prime (81221983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40610981 + 40610982.

It is an arithmetic number, because the mean of its divisors is an integer number (40610982).

Almost surely, 2^81221963 is an apocalyptic number.

81221963 is a deficient number, since it is larger than the sum of its proper divisors (1).

81221963 is an equidigital number, since it uses as much as digits as its factorization.

81221963 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5184, while the sum is 32.

The square root of 81221963 is about 9012.3228415320. The cubic root of 81221963 is about 433.0697279733.

The spelling of 81221963 in words is "eighty-one million, two hundred twenty-one thousand, nine hundred sixty-three".