18491920225 has 9 divisors (see below), whose sum is σ = 22930824217. Its totient is φ = 14792992240.

The previous prime is 18491920211. The next prime is 18491920231. The reversal of 18491920225 is 52202919481.

The square root of 18491920225 is 135985.

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

It can be written as a sum of positive squares in 4 ways, for example, as 143592289 + 18348327936 = 11983^2 + 135456^2 .

It is not a de Polignac number, because 18491920225 - 2²³ = 18483531617 is a prime.

It is a super-2 number, since 2×18491920225² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 666327 + ... + 693523.

Almost surely, 2^18491920225 is an apocalyptic number.

18491920225 is the 135985-th square number.

18491920225 is the 67993-rd centered octagonal number.

It is an amenable number.

18491920225 is a deficient number, since it is larger than the sum of its proper divisors (4438903992).

18491920225 is an frugal number, since it uses more digits than its factorization.

18491920225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54404 (or 27202 counting only the distinct ones).

The product of its (nonzero) digits is 103680, while the sum is 43.

The spelling of 18491920225 in words is "eighteen billion, four hundred ninety-one million, nine hundred twenty thousand, two hundred twenty-five".