81201992 has 8 divisors (see below), whose sum is σ = 152253750. Its totient is φ = 40600992.

The previous prime is 81201973. The next prime is 81201997. The reversal of 81201992 is 29910218.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 76983076 + 4218916 = 8774^2 + 2054^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is not an unprimeable number, because it can be changed into a prime (81201997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5075117 + ... + 5075132.

Almost surely, 2^81201992 is an apocalyptic number.

It is an amenable number.

81201992 is a deficient number, since it is larger than the sum of its proper divisors (71051758).

81201992 is a wasteful number, since it uses less digits than its factorization.

81201992 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10150255 (or 10150251 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 32.

The square root of 81201992 is about 9011.2147904708. The cubic root of 81201992 is about 433.0342304133.

The spelling of 81201992 in words is "eighty-one million, two hundred one thousand, nine hundred ninety-two".