72106981 has 4 divisors (see below), whose sum is σ = 72198252. Its totient is φ = 72015712.

The previous prime is 72106913. The next prime is 72107003. The reversal of 72106981 is 18960127.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 47196900 + 24910081 = 6870^2 + 4991^2 .

It is a cyclic number.

It is not a de Polignac number, because 72106981 - 2¹⁵ = 72074213 is a prime.

It is a super-2 number, since 2×72106981² = 10398833417868722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (72106481) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 44440 + ... + 46033.

It is an arithmetic number, because the mean of its divisors is an integer number (18049563).

Almost surely, 2^72106981 is an apocalyptic number.

It is an amenable number.

72106981 is a deficient number, since it is larger than the sum of its proper divisors (91271).

72106981 is an equidigital number, since it uses as much as digits as its factorization.

72106981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91270.

The product of its (nonzero) digits is 6048, while the sum is 34.

The square root of 72106981 is about 8491.5829501925. The cubic root of 72106981 is about 416.2227084284. Note that the first 3 decimals are identical.

The spelling of 72106981 in words is "seventy-two million, one hundred six thousand, nine hundred eighty-one".