391154021 has 16 divisors (see below), whose sum is σ = 406335600. Its totient is φ = 376358400.

The previous prime is 391154009. The next prime is 391154041. The reversal of 391154021 is 120451193.

It can be written as a sum of positive squares in 8 ways, for example, as 16924996 + 374229025 = 4114^2 + 19345^2 .

It is a cyclic number.

It is not a de Polignac number, because 391154021 - 2²² = 386959717 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 (391154041) 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 15 ways as a sum of consecutive naturals, for example, 591431 + ... + 592091.

It is an arithmetic number, because the mean of its divisors is an integer number (25395975).

Almost surely, 2^391154021 is an apocalyptic number.

It is an amenable number.

391154021 is a deficient number, since it is larger than the sum of its proper divisors (15181579).

391154021 is a wasteful number, since it uses less digits than its factorization.

391154021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 920.

The product of its (nonzero) digits is 1080, while the sum is 26.

The square root of 391154021 is about 19777.6141382119. The cubic root of 391154021 is about 731.3342839418.

The spelling of 391154021 in words is "three hundred ninety-one million, one hundred fifty-four thousand, twenty-one".