396121981 has 4 divisors (see below), whose sum is σ = 419423292. Its totient is φ = 372820672.

The previous prime is 396121961. The next prime is 396121987. The reversal of 396121981 is 189121693.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 189121693 = 1571 ⋅120383.

It can be written as a sum of positive squares in 2 ways, for example, as 152917956 + 243204025 = 12366^2 + 15595^2 .

It is a cyclic number.

It is not a de Polignac number, because 396121981 - 2⁵ = 396121949 is a prime.

It is a super-2 number, since 2×396121981² = 313825247662728722, 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 (396121987) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11650630 + ... + 11650663.

It is an arithmetic number, because the mean of its divisors is an integer number (104855823).

Almost surely, 2^396121981 is an apocalyptic number.

It is an amenable number.

396121981 is a deficient number, since it is larger than the sum of its proper divisors (23301311).

396121981 is a wasteful number, since it uses less digits than its factorization.

396121981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23301310.

The product of its digits is 23328, while the sum is 40.

The square root of 396121981 is about 19902.8133940908. The cubic root of 396121981 is about 734.4174389502.

The spelling of 396121981 in words is "three hundred ninety-six million, one hundred twenty-one thousand, nine hundred eighty-one".