21531223037 has 2 divisors, whose sum is σ = 21531223038. Its totient is φ = 21531223036.

The previous prime is 21531222983. The next prime is 21531223057. The reversal of 21531223037 is 73032213512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21403397401 + 127825636 = 146299^2 + 11306^2 .

It is a cyclic number.

It is not a de Polignac number, because 21531223037 - 2¹² = 21531218941 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21531223057) 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, 10765611518 + 10765611519.

It is an arithmetic number, because the mean of its divisors is an integer number (10765611519).

Almost surely, 2^21531223037 is an apocalyptic number.

It is an amenable number.

21531223037 is a deficient number, since it is larger than the sum of its proper divisors (1).

21531223037 is an equidigital number, since it uses as much as digits as its factorization.

21531223037 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7560, while the sum is 29.

Adding to 21531223037 its reverse (73032213512), we get a palindrome (94563436549).

The spelling of 21531223037 in words is "twenty-one billion, five hundred thirty-one million, two hundred twenty-three thousand, thirty-seven".