66691903 has 2 divisors, whose sum is σ = 66691904. Its totient is φ = 66691902.

The previous prime is 66691897. The next prime is 66691931. The reversal of 66691903 is 30919666.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66691903 is a prime.

It is a super-2 number, since 2×66691903² = 8895619851522818, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66691003) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33345951 + 33345952.

It is an arithmetic number, because the mean of its divisors is an integer number (33345952).

Almost surely, 2^66691903 is an apocalyptic number.

66691903 is a deficient number, since it is larger than the sum of its proper divisors (1).

66691903 is an equidigital number, since it uses as much as digits as its factorization.

66691903 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 52488, while the sum is 40.

The square root of 66691903 is about 8166.5110665449. The cubic root of 66691903 is about 405.5312907426.

The spelling of 66691903 in words is "sixty-six million, six hundred ninety-one thousand, nine hundred three".