21453506831 has 2 divisors, whose sum is σ = 21453506832. Its totient is φ = 21453506830.

The previous prime is 21453506819. The next prime is 21453506839. The reversal of 21453506831 is 13860535412.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21453506831 - 2¹⁰ = 21453505807 is a prime.

It is a super-2 number, since 2×21453506831² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21453506839) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10726753415 + 10726753416.

It is an arithmetic number, because the mean of its divisors is an integer number (10726753416).

Almost surely, 2^21453506831 is an apocalyptic number.

21453506831 is a deficient number, since it is larger than the sum of its proper divisors (1).

21453506831 is an equidigital number, since it uses as much as digits as its factorization.

21453506831 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 86400, while the sum is 38.

The spelling of 21453506831 in words is "twenty-one billion, four hundred fifty-three million, five hundred six thousand, eight hundred thirty-one".