19138785649 has 9 divisors (see below), whose sum is σ = 19675292427. Its totient is φ = 18616540824.

The previous prime is 19138785647. The next prime is 19138785661. The reversal of 19138785649 is 94658783191.

The square root of 19138785649 is 138343.

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., 17125648225 + 2013137424 = 130865^2 + 44868^2 .

It is not a de Polignac number, because 19138785649 - 2¹ = 19138785647 is a prime.

It is a super-2 number, since 2×19138785649² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19138785641) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 5116822 + ... + 5120560.

It is an arithmetic number, because the mean of its divisors is an integer number (2186143603).

Almost surely, 2^19138785649 is an apocalyptic number.

19138785649 is the 138343-rd square number.

19138785649 is the 69172-nd centered octagonal number.

It is an amenable number.

19138785649 is a deficient number, since it is larger than the sum of its proper divisors (536506778).

19138785649 is an frugal number, since it uses more digits than its factorization.

19138785649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7552 (or 3776 counting only the distinct ones).

The product of its digits is 13063680, while the sum is 61.

The spelling of 19138785649 in words is "nineteen billion, one hundred thirty-eight million, seven hundred eighty-five thousand, six hundred forty-nine".