21155055001 has 2 divisors, whose sum is σ = 21155055002. Its totient is φ = 21155055000.

The previous prime is 21155054971. The next prime is 21155055013. The reversal of 21155055001 is 10055055112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20645379225 + 509675776 = 143685^2 + 22576^2 .

It is a cyclic number.

It is not a de Polignac number, because 21155055001 - 2⁵ = 21155054969 is a prime.

It is a super-2 number, since 2×21155055001² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21155059001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10577527500 + 10577527501.

It is an arithmetic number, because the mean of its divisors is an integer number (10577527501).

Almost surely, 2^21155055001 is an apocalyptic number.

It is an amenable number.

21155055001 is a deficient number, since it is larger than the sum of its proper divisors (1).

21155055001 is an equidigital number, since it uses as much as digits as its factorization.

21155055001 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1250, while the sum is 25.

The spelling of 21155055001 in words is "twenty-one billion, one hundred fifty-five million, fifty-five thousand, one".