81670051 has 2 divisors, whose sum is σ = 81670052. Its totient is φ = 81670050.

The previous prime is 81670031. The next prime is 81670081. The reversal of 81670051 is 15007618.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81670051 - 2⁵ = 81670019 is a prime.

It is not a weakly prime, because it can be changed into another prime (81670031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40835025 + 40835026.

It is an arithmetic number, because the mean of its divisors is an integer number (40835026).

Almost surely, 2^81670051 is an apocalyptic number.

81670051 is a deficient number, since it is larger than the sum of its proper divisors (1).

81670051 is an equidigital number, since it uses as much as digits as its factorization.

81670051 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1680, while the sum is 28.

The square root of 81670051 is about 9037.1483887341. The cubic root of 81670051 is about 433.8646590384.

Adding to 81670051 its reverse (15007618), we get a palindrome (96677669).

The spelling of 81670051 in words is "eighty-one million, six hundred seventy thousand, fifty-one".