21451431437 has 2 divisors, whose sum is σ = 21451431438. Its totient is φ = 21451431436.

The previous prime is 21451431403. The next prime is 21451431479. The reversal of 21451431437 is 73413415412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14605689316 + 6845742121 = 120854^2 + 82739^2 .

It is a cyclic number.

It is not a de Polignac number, because 21451431437 - 2¹² = 21451427341 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21451431397 and 21451431406.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21451431037) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10725715718 + 10725715719.

It is an arithmetic number, because the mean of its divisors is an integer number (10725715719).

Almost surely, 2^21451431437 is an apocalyptic number.

It is an amenable number.

21451431437 is a deficient number, since it is larger than the sum of its proper divisors (1).

21451431437 is an equidigital number, since it uses as much as digits as its factorization.

21451431437 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 40320, while the sum is 35.

Adding to 21451431437 its reverse (73413415412), we get a palindrome (94864846849).

The spelling of 21451431437 in words is "twenty-one billion, four hundred fifty-one million, four hundred thirty-one thousand, four hundred thirty-seven".