19438890649 has 2 divisors, whose sum is σ = 19438890650. Its totient is φ = 19438890648.

The previous prime is 19438890643. The next prime is 19438890661. The reversal of 19438890649 is 94609883491.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12095600400 + 7343290249 = 109980^2 + 85693^2 .

It is a cyclic number.

It is not a de Polignac number, because 19438890649 - 2³ = 19438890641 is a prime.

It is not a weakly prime, because it can be changed into another prime (19438890641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9719445324 + 9719445325.

It is an arithmetic number, because the mean of its divisors is an integer number (9719445325).

Almost surely, 2^19438890649 is an apocalyptic number.

It is an amenable number.

19438890649 is a deficient number, since it is larger than the sum of its proper divisors (1).

19438890649 is an equidigital number, since it uses as much as digits as its factorization.

19438890649 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 13436928, while the sum is 61.

The spelling of 19438890649 in words is "nineteen billion, four hundred thirty-eight million, eight hundred ninety thousand, six hundred forty-nine".