66570991 has 2 divisors, whose sum is σ = 66570992. Its totient is φ = 66570990.

The previous prime is 66570989. The next prime is 66571007. The reversal of 66570991 is 19907566.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 66570991 - 2¹ = 66570989 is a prime.

Together with 66570989, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66570961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33285495 + 33285496.

It is an arithmetic number, because the mean of its divisors is an integer number (33285496).

Almost surely, 2^66570991 is an apocalyptic number.

66570991 is a deficient number, since it is larger than the sum of its proper divisors (1).

66570991 is an equidigital number, since it uses as much as digits as its factorization.

66570991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 102060, while the sum is 43.

The square root of 66570991 is about 8159.1047915810. The cubic root of 66570991 is about 405.2860672615.

The spelling of 66570991 in words is "sixty-six million, five hundred seventy thousand, nine hundred ninety-one".