391213281 has 4 divisors (see below), whose sum is σ = 521617712. Its totient is φ = 260808852.

The previous prime is 391213259. The next prime is 391213283. The reversal of 391213281 is 182312193.

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 not a de Polignac number, because 391213281 - 2²² = 387018977 is a prime.

It is a super-2 number, since 2×391213281² = 306095662461569922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (391213283) 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, 65202211 + ... + 65202216.

It is an arithmetic number, because the mean of its divisors is an integer number (130404428).

Almost surely, 2^391213281 is an apocalyptic number.

It is an amenable number.

391213281 is a deficient number, since it is larger than the sum of its proper divisors (130404431).

391213281 is a wasteful number, since it uses less digits than its factorization.

391213281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 130404430.

The product of its digits is 2592, while the sum is 30.

The square root of 391213281 is about 19779.1122399364. The cubic root of 391213281 is about 731.3712145615.

The spelling of 391213281 in words is "three hundred ninety-one million, two hundred thirteen thousand, two hundred eighty-one".