390278981 has 4 divisors (see below), whose sum is σ = 410820000. Its totient is φ = 369737964.

The previous prime is 390278971. The next prime is 390279053. The reversal of 390278981 is 189872093.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 189872093 = 5741 ⋅33073.

It is a cyclic number.

It is not a de Polignac number, because 390278981 - 2¹⁰ = 390277957 is a prime.

It is a super-2 number, since 2×390278981² = 304635366020796722, 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 (390278971) 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, 10270481 + ... + 10270518.

It is an arithmetic number, because the mean of its divisors is an integer number (102705000).

Almost surely, 2^390278981 is an apocalyptic number.

It is an amenable number.

390278981 is a deficient number, since it is larger than the sum of its proper divisors (20541019).

390278981 is a wasteful number, since it uses less digits than its factorization.

390278981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20541018.

The product of its (nonzero) digits is 217728, while the sum is 47.

The square root of 390278981 is about 19755.4797714457. The cubic root of 390278981 is about 730.7885274419.

The spelling of 390278981 in words is "three hundred ninety million, two hundred seventy-eight thousand, nine hundred eighty-one".