21656246123 has 2 divisors, whose sum is σ = 21656246124. Its totient is φ = 21656246122.

The previous prime is 21656246119. The next prime is 21656246141. The reversal of 21656246123 is 32164265612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21656246123 - 2² = 21656246119 is a prime.

It is a super-2 number, since 2×21656246123² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21656246723) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10828123061 + 10828123062.

It is an arithmetic number, because the mean of its divisors is an integer number (10828123062).

Almost surely, 2^21656246123 is an apocalyptic number.

21656246123 is a deficient number, since it is larger than the sum of its proper divisors (1).

21656246123 is an equidigital number, since it uses as much as digits as its factorization.

21656246123 is an evil number, because the sum of its binary digits is even.

The product of its digits is 103680, while the sum is 38.

The spelling of 21656246123 in words is "twenty-one billion, six hundred fifty-six million, two hundred forty-six thousand, one hundred twenty-three".