640981219 has 2 divisors, whose sum is σ = 640981220. Its totient is φ = 640981218.

The previous prime is 640981183. The next prime is 640981223. The reversal of 640981219 is 912189046.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640981219 is a prime.

It is a super-2 number, since 2×640981219² = 821713846221451922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (640981619) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320490609 + 320490610.

It is an arithmetic number, because the mean of its divisors is an integer number (320490610).

Almost surely, 2^640981219 is an apocalyptic number.

640981219 is a deficient number, since it is larger than the sum of its proper divisors (1).

640981219 is an equidigital number, since it uses as much as digits as its factorization.

640981219 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 31104, while the sum is 40.

The square root of 640981219 is about 25317.6068971773. The cubic root of 640981219 is about 862.2140620175.

The spelling of 640981219 in words is "six hundred forty million, nine hundred eighty-one thousand, two hundred nineteen".