521139191 has 4 divisors (see below), whose sum is σ = 535224072. Its totient is φ = 507054312.

The previous prime is 521139173. The next prime is 521139197. The reversal of 521139191 is 191931125.

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

It is a cyclic number.

It is not a de Polignac number, because 521139191 - 2¹⁴ = 521122807 is a prime.

It is a super-2 number, since 2×521139191² = 543172112792268962, 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 (521139197) 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, 7042385 + ... + 7042458.

It is an arithmetic number, because the mean of its divisors is an integer number (133806018).

Almost surely, 2^521139191 is an apocalyptic number.

521139191 is a deficient number, since it is larger than the sum of its proper divisors (14084881).

521139191 is a wasteful number, since it uses less digits than its factorization.

521139191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14084880.

The product of its digits is 2430, while the sum is 32.

The square root of 521139191 is about 22828.4732516215. The cubic root of 521139191 is about 804.7319509282.

The spelling of 521139191 in words is "five hundred twenty-one million, one hundred thirty-nine thousand, one hundred ninety-one".