21124199531 has 2 divisors, whose sum is σ = 21124199532. Its totient is φ = 21124199530.

The previous prime is 21124199513. The next prime is 21124199611. The reversal of 21124199531 is 13599142112.

Together with previous prime (21124199513) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21124199531 - 2²² = 21120005227 is a prime.

It is a super-2 number, since 2×21124199531² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21124199501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10562099765 + 10562099766.

It is an arithmetic number, because the mean of its divisors is an integer number (10562099766).

Almost surely, 2^21124199531 is an apocalyptic number.

21124199531 is a deficient number, since it is larger than the sum of its proper divisors (1).

21124199531 is an equidigital number, since it uses as much as digits as its factorization.

21124199531 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 19440, while the sum is 38.

The spelling of 21124199531 in words is "twenty-one billion, one hundred twenty-four million, one hundred ninety-nine thousand, five hundred thirty-one".