531139681 has 4 divisors (see below), whose sum is σ = 531454000. Its totient is φ = 530825364.

The previous prime is 531139639. The next prime is 531139729. The reversal of 531139681 is 186931135.

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, and also an emirpimes, since its reverse is a distinct semiprime: 186931135 = 5 ⋅37386227.

It is a cyclic number.

It is not a de Polignac number, because 531139681 - 2¹⁷ = 531008609 is a prime.

It is a super-2 number, since 2×531139681² = 564218721465563522, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 531139681.

It is not an unprimeable number, because it can be changed into a prime (531139601) 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, 154611 + ... + 158008.

It is an arithmetic number, because the mean of its divisors is an integer number (132863500).

Almost surely, 2^531139681 is an apocalyptic number.

It is an amenable number.

531139681 is a deficient number, since it is larger than the sum of its proper divisors (314319).

531139681 is a wasteful number, since it uses less digits than its factorization.

531139681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 314318.

The product of its digits is 19440, while the sum is 37.

The square root of 531139681 is about 23046.4678638615. The cubic root of 531139681 is about 809.8468851467.

The spelling of 531139681 in words is "five hundred thirty-one million, one hundred thirty-nine thousand, six hundred eighty-one".