391135421 has 4 divisors (see below), whose sum is σ = 392527644. Its totient is φ = 389743200.

The previous prime is 391135417. The next prime is 391135429. The reversal of 391135421 is 124531193.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 134815321 + 256320100 = 11611^2 + 16010^2 .

It is a cyclic number.

It is not a de Polignac number, because 391135421 - 2² = 391135417 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (391135429) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 695690 + ... + 696251.

It is an arithmetic number, because the mean of its divisors is an integer number (98131911).

Almost surely, 2^391135421 is an apocalyptic number.

It is an amenable number.

391135421 is a deficient number, since it is larger than the sum of its proper divisors (1392223).

391135421 is a wasteful number, since it uses less digits than its factorization.

391135421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1392222.

The product of its digits is 3240, while the sum is 29.

The square root of 391135421 is about 19777.1439040120. The cubic root of 391135421 is about 731.3226917193.

The spelling of 391135421 in words is "three hundred ninety-one million, one hundred thirty-five thousand, four hundred twenty-one".