21012190217 has 2 divisors, whose sum is σ = 21012190218. Its totient is φ = 21012190216.

The previous prime is 21012190153. The next prime is 21012190237. The reversal of 21012190217 is 71209121012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19081554496 + 1930635721 = 138136^2 + 43939^2 .

It is a cyclic number.

It is not a de Polignac number, because 21012190217 - 2⁶ = 21012190153 is a prime.

It is not a weakly prime, because it can be changed into another prime (21012190237) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10506095108 + 10506095109.

It is an arithmetic number, because the mean of its divisors is an integer number (10506095109).

Almost surely, 2^21012190217 is an apocalyptic number.

It is an amenable number.

21012190217 is a deficient number, since it is larger than the sum of its proper divisors (1).

21012190217 is an equidigital number, since it uses as much as digits as its factorization.

21012190217 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 504, while the sum is 26.

The spelling of 21012190217 in words is "twenty-one billion, twelve million, one hundred ninety thousand, two hundred seventeen".