21861311629 has 2 divisors, whose sum is σ = 21861311630. Its totient is φ = 21861311628.

The previous prime is 21861311627. The next prime is 21861311683. The reversal of 21861311629 is 92611316812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19711598404 + 2149713225 = 140398^2 + 46365^2 .

It is a cyclic number.

It is not a de Polignac number, because 21861311629 - 2¹ = 21861311627 is a prime.

It is a super-2 number, since 2×21861311629² (a number of 21 digits) contains 22 as substring.

Together with 21861311627, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 21861311591 and 21861311600.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21861311627) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10930655814 + 10930655815.

It is an arithmetic number, because the mean of its divisors is an integer number (10930655815).

Almost surely, 2^21861311629 is an apocalyptic number.

It is an amenable number.

21861311629 is a deficient number, since it is larger than the sum of its proper divisors (1).

21861311629 is an equidigital number, since it uses as much as digits as its factorization.

21861311629 is an evil number, because the sum of its binary digits is even.

The product of its digits is 31104, while the sum is 40.

The spelling of 21861311629 in words is "twenty-one billion, eight hundred sixty-one million, three hundred eleven thousand, six hundred twenty-nine".