81993025 has 9 divisors (see below), whose sum is σ = 101727523. Its totient is φ = 65558200.

The previous prime is 81993017. The next prime is 81993029. The reversal of 81993025 is 52039918.

The square root of 81993025 is 9055.

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., 29517489 + 52475536 = 5433^2 + 7244^2 .

It is not a de Polignac number, because 81993025 - 2³ = 81993017 is a prime.

It is a super-2 number, since 2×81993025² = 13445712297301250, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81993029) 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, 44370 + ... + 46180.

Almost surely, 2^81993025 is an apocalyptic number.

81993025 is the 9055-th square number.

81993025 is the 4528-th centered octagonal number.

It is an amenable number.

81993025 is a deficient number, since it is larger than the sum of its proper divisors (19734498).

81993025 is an frugal number, since it uses more digits than its factorization.

81993025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3632 (or 1816 counting only the distinct ones).

The product of its (nonzero) digits is 19440, while the sum is 37.

The cubic root of 81993025 is about 434.4358300331.

The spelling of 81993025 in words is "eighty-one million, nine hundred ninety-three thousand, twenty-five".