73978981 has 2 divisors, whose sum is σ = 73978982. Its totient is φ = 73978980.

The previous prime is 73978973. The next prime is 73978991. The reversal of 73978981 is 18987937.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 73256481 + 722500 = 8559^2 + 850^2 .

It is an emirp because it is prime and its reverse (18987937) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 73978981 - 2³ = 73978973 is a prime.

It is a super-2 number, since 2×73978981² = 10945779259596722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (73978991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36989490 + 36989491.

It is an arithmetic number, because the mean of its divisors is an integer number (36989491).

Almost surely, 2^73978981 is an apocalyptic number.

It is an amenable number.

73978981 is a deficient number, since it is larger than the sum of its proper divisors (1).

73978981 is an equidigital number, since it uses as much as digits as its factorization.

73978981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 762048, while the sum is 52.

The square root of 73978981 is about 8601.1034757175. The cubic root of 73978981 is about 419.7938916915.

The spelling of 73978981 in words is "seventy-three million, nine hundred seventy-eight thousand, nine hundred eighty-one".