64691999 has 2 divisors, whose sum is σ = 64692000. Its totient is φ = 64691998.

The previous prime is 64691993. The next prime is 64692037. The reversal of 64691999 is 99919646.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 64691999 - 2⁴ = 64691983 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 64691999.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (64691993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32345999 + 32346000.

It is an arithmetic number, because the mean of its divisors is an integer number (32346000).

Almost surely, 2^64691999 is an apocalyptic number.

64691999 is a deficient number, since it is larger than the sum of its proper divisors (1).

64691999 is an equidigital number, since it uses as much as digits as its factorization.

64691999 is an evil number, because the sum of its binary digits is even.

The product of its digits is 944784, while the sum is 53.

The square root of 64691999 is about 8043.1336554853. The cubic root of 64691999 is about 401.4364995802.

The spelling of 64691999 in words is "sixty-four million, six hundred ninety-one thousand, nine hundred ninety-nine".