81640007 has 2 divisors, whose sum is σ = 81640008. Its totient is φ = 81640006.

The previous prime is 81640003. The next prime is 81640049. The reversal of 81640007 is 70004618.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81640007 - 2² = 81640003 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81640003) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40820003 + 40820004.

It is an arithmetic number, because the mean of its divisors is an integer number (40820004).

Almost surely, 2^81640007 is an apocalyptic number.

81640007 is a deficient number, since it is larger than the sum of its proper divisors (1).

81640007 is an equidigital number, since it uses as much as digits as its factorization.

81640007 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1344, while the sum is 26.

The square root of 81640007 is about 9035.4859858228. The cubic root of 81640007 is about 433.8114505147.

The spelling of 81640007 in words is "eighty-one million, six hundred forty thousand, seven".