391450981 has 4 divisors (see below), whose sum is σ = 404078464. Its totient is φ = 378823500.

The previous prime is 391450979. The next prime is 391451003. The reversal of 391450981 is 189054193.

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.

It is a cyclic number.

It is not a de Polignac number, because 391450981 - 2¹ = 391450979 is a prime.

It is a super-2 number, since 2×391450981² = 306467741051724722, 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 (391450181) 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, 6313695 + ... + 6313756.

It is an arithmetic number, because the mean of its divisors is an integer number (101019616).

Almost surely, 2^391450981 is an apocalyptic number.

391450981 is a gapful number since it is divisible by the number (31) formed by its first and last digit.

It is an amenable number.

391450981 is a deficient number, since it is larger than the sum of its proper divisors (12627483).

391450981 is a wasteful number, since it uses less digits than its factorization.

391450981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12627482.

The product of its (nonzero) digits is 38880, while the sum is 40.

The square root of 391450981 is about 19785.1201916996. The cubic root of 391450981 is about 731.5193108800.

The spelling of 391450981 in words is "three hundred ninety-one million, four hundred fifty thousand, nine hundred eighty-one".