21122011957 has 2 divisors, whose sum is σ = 21122011958. Its totient is φ = 21122011956.

The previous prime is 21122011877. The next prime is 21122011973. The reversal of 21122011957 is 75911022112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21121971556 + 40401 = 145334^2 + 201^2 .

It is a cyclic number.

It is not a de Polignac number, because 21122011957 - 2¹⁵ = 21121979189 is a prime.

It is a super-2 number, since 2×21122011957² (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 (21122011987) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10561005978 + 10561005979.

It is an arithmetic number, because the mean of its divisors is an integer number (10561005979).

Almost surely, 2^21122011957 is an apocalyptic number.

It is an amenable number.

21122011957 is a deficient number, since it is larger than the sum of its proper divisors (1).

21122011957 is an equidigital number, since it uses as much as digits as its factorization.

21122011957 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2520, while the sum is 31.

The spelling of 21122011957 in words is "twenty-one billion, one hundred twenty-two million, eleven thousand, nine hundred fifty-seven".