21154521031631 has 12 divisors (see below), whose sum is σ = 22935716285832. Its totient is φ = 19396194548064.

The previous prime is 21154521031561. The next prime is 21154521031663. The reversal of 21154521031631 is 13613012545112.

It is a happy number.

It is a de Polignac number, because none of the positive numbers 2^k-21154521031631 is a prime.

It is a super-2 number, since 2×21154521031631² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21154521031591 and 21154521031600.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21154521031031) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 36359981 + ... + 36937206.

It is an arithmetic number, because the mean of its divisors is an integer number (1911309690486).

Almost surely, 2^{21154521031631} is an apocalyptic number.

21154521031631 is a deficient number, since it is larger than the sum of its proper divisors (1781195254201).

21154521031631 is an equidigital number, since it uses as much as digits as its factorization.

21154521031631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73297498 (or 73297349 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 35.

Adding to 21154521031631 its reverse (13613012545112), we get a palindrome (34767533576743).

The spelling of 21154521031631 in words is "twenty-one trillion, one hundred fifty-four billion, five hundred twenty-one million, thirty-one thousand, six hundred thirty-one".