521538626381 has 2 divisors, whose sum is σ = 521538626382. Its totient is φ = 521538626380.

The previous prime is 521538626351. The next prime is 521538626471. The reversal of 521538626381 is 183626835125.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 290018869156 + 231519757225 = 538534^2 + 481165^2 .

It is a cyclic number.

It is not a de Polignac number, because 521538626381 - 2²² = 521534432077 is a prime.

It is a super-2 number, since 2×521538626381² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (521538626321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 260769313190 + 260769313191.

It is an arithmetic number, because the mean of its divisors is an integer number (260769313191).

Almost surely, 2^521538626381 is an apocalyptic number.

It is an amenable number.

521538626381 is a deficient number, since it is larger than the sum of its proper divisors (1).

521538626381 is an equidigital number, since it uses as much as digits as its factorization.

521538626381 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2073600, while the sum is 50.

The spelling of 521538626381 in words is "five hundred twenty-one billion, five hundred thirty-eight million, six hundred twenty-six thousand, three hundred eighty-one".