21946172051 has 2 divisors, whose sum is σ = 21946172052. Its totient is φ = 21946172050.

The previous prime is 21946172021. The next prime is 21946172089. The reversal of 21946172051 is 15027164912.

It is an a-pointer prime, because the next prime (21946172089) can be obtained adding 21946172051 to its sum of digits (38).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21946172051 - 2²² = 21941977747 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21946171996 and 21946172014.

It is not a weakly prime, because it can be changed into another prime (21946172021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10973086025 + 10973086026.

It is an arithmetic number, because the mean of its divisors is an integer number (10973086026).

Almost surely, 2^21946172051 is an apocalyptic number.

21946172051 is a deficient number, since it is larger than the sum of its proper divisors (1).

21946172051 is an equidigital number, since it uses as much as digits as its factorization.

21946172051 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 30240, while the sum is 38.

The spelling of 21946172051 in words is "twenty-one billion, nine hundred forty-six million, one hundred seventy-two thousand, fifty-one".