81953513 has 2 divisors, whose sum is σ = 81953514. Its totient is φ = 81953512.

The previous prime is 81953471. The next prime is 81953533. The reversal of 81953513 is 31535918.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 79798489 + 2155024 = 8933^2 + 1468^2 .

It is a cyclic number.

It is not a de Polignac number, because 81953513 - 2¹⁶ = 81887977 is a prime.

It is not a weakly prime, because it can be changed into another prime (81953533) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40976756 + 40976757.

It is an arithmetic number, because the mean of its divisors is an integer number (40976757).

Almost surely, 2^81953513 is an apocalyptic number.

It is an amenable number.

81953513 is a deficient number, since it is larger than the sum of its proper divisors (1).

81953513 is an equidigital number, since it uses as much as digits as its factorization.

81953513 is an evil number, because the sum of its binary digits is even.

The product of its digits is 16200, while the sum is 35.

The square root of 81953513 is about 9052.8179590667. The cubic root of 81953513 is about 434.3660347200.

The spelling of 81953513 in words is "eighty-one million, nine hundred fifty-three thousand, five hundred thirteen".