644154899 has 2 divisors, whose sum is σ = 644154900. Its totient is φ = 644154898.

The previous prime is 644154877. The next prime is 644154991. The reversal of 644154899 is 998451446.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 644154899 - 2¹² = 644150803 is a prime.

It is not a weakly prime, because it can be changed into another prime (644154809) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322077449 + 322077450.

It is an arithmetic number, because the mean of its divisors is an integer number (322077450).

Almost surely, 2^644154899 is an apocalyptic number.

644154899 is a deficient number, since it is larger than the sum of its proper divisors (1).

644154899 is an equidigital number, since it uses as much as digits as its factorization.

644154899 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1244160, while the sum is 50.

The square root of 644154899 is about 25380.2068352486. The cubic root of 644154899 is about 863.6347420666.

The spelling of 644154899 in words is "six hundred forty-four million, one hundred fifty-four thousand, eight hundred ninety-nine".