340399981 has 2 divisors, whose sum is σ = 340399982. Its totient is φ = 340399980.

The previous prime is 340399951. The next prime is 340400017. The reversal of 340399981 is 189993043.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 319193956 + 21206025 = 17866^2 + 4605^2 .

It is an emirp because it is prime and its reverse (189993043) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 340399981 - 2⁷ = 340399853 is a prime.

It is a super-2 number, since 2×340399981² = 231744294129600722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (340399901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 170199990 + 170199991.

It is an arithmetic number, because the mean of its divisors is an integer number (170199991).

Almost surely, 2^340399981 is an apocalyptic number.

It is an amenable number.

340399981 is a deficient number, since it is larger than the sum of its proper divisors (1).

340399981 is an equidigital number, since it uses as much as digits as its factorization.

340399981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 209952, while the sum is 46.

The square root of 340399981 is about 18449.9317342911. The cubic root of 340399981 is about 698.2267915730.

The spelling of 340399981 in words is "three hundred forty million, three hundred ninety-nine thousand, nine hundred eighty-one".