19900904647849 has 9 divisors (see below), whose sum is σ = 20085647541687. Its totient is φ = 19717845748344.

The previous prime is 19900904647847. The next prime is 19900904647879. The reversal of 19900904647849 is 94874640900991.

The square root of 19900904647849 is 4461043.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 13870835063449 + 6030069584400 = 3724357^2 + 2455620^2 .

It is not a de Polignac number, because 19900904647849 - 2¹ = 19900904647847 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19900904647847) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 486233224 + ... + 486274150.

It is an arithmetic number, because the mean of its divisors is an integer number (2231738615743).

Almost surely, 2^{19900904647849} is an apocalyptic number.

19900904647849 is the 4461043-rd square number.

19900904647849 is the 2230522-nd centered octagonal number.

It is an amenable number.

19900904647849 is a deficient number, since it is larger than the sum of its proper divisors (184742893838).

19900904647849 is an frugal number, since it uses more digits than its factorization.

19900904647849 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82072 (or 41036 counting only the distinct ones).

The product of its (nonzero) digits is 141087744, while the sum is 70.

The spelling of 19900904647849 in words is "nineteen trillion, nine hundred billion, nine hundred four million, six hundred forty-seven thousand, eight hundred forty-nine".