81923537 has 2 divisors, whose sum is σ = 81923538. Its totient is φ = 81923536.

The previous prime is 81923507. The next prime is 81923551. The reversal of 81923537 is 73532918.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 70627216 + 11296321 = 8404^2 + 3361^2 .

It is a cyclic number.

It is not a de Polignac number, because 81923537 - 2⁶ = 81923473 is a prime.

It is a super-2 number, since 2×81923537² = 13422931829180738, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81923537.

It is not a weakly prime, because it can be changed into another prime (81923507) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40961768 + 40961769.

It is an arithmetic number, because the mean of its divisors is an integer number (40961769).

Almost surely, 2^81923537 is an apocalyptic number.

It is an amenable number.

81923537 is a deficient number, since it is larger than the sum of its proper divisors (1).

81923537 is an equidigital number, since it uses as much as digits as its factorization.

81923537 is an evil number, because the sum of its binary digits is even.

The product of its digits is 45360, while the sum is 38.

The square root of 81923537 is about 9051.1621905698. The cubic root of 81923537 is about 434.3130691480.

The spelling of 81923537 in words is "eighty-one million, nine hundred twenty-three thousand, five hundred thirty-seven".