81961967 has 2 divisors, whose sum is σ = 81961968. Its totient is φ = 81961966.

The previous prime is 81961961. The next prime is 81961987. The reversal of 81961967 is 76916918.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81961967 - 2¹⁴ = 81945583 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81961961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40980983 + 40980984.

It is an arithmetic number, because the mean of its divisors is an integer number (40980984).

Almost surely, 2^81961967 is an apocalyptic number.

81961967 is a deficient number, since it is larger than the sum of its proper divisors (1).

81961967 is an equidigital number, since it uses as much as digits as its factorization.

81961967 is an evil number, because the sum of its binary digits is even.

The product of its digits is 163296, while the sum is 47.

The square root of 81961967 is about 9053.2848734589. The cubic root of 81961967 is about 434.3809700334.

It can be divided in two parts, 81961 and 967, that added together give a palindrome (82928).

The spelling of 81961967 in words is "eighty-one million, nine hundred sixty-one thousand, nine hundred sixty-seven".