21020019999973 has 2 divisors, whose sum is σ = 21020019999974. Its totient is φ = 21020019999972.

The previous prime is 21020019999899. The next prime is 21020019999991. The reversal of 21020019999973 is 37999991002012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19018861767844 + 2001158232129 = 4361062^2 + 1414623^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21020019999973 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21020019996973) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510009999986 + 10510009999987.

It is an arithmetic number, because the mean of its divisors is an integer number (10510009999987).

Almost surely, 2^{21020019999973} is an apocalyptic number.

It is an amenable number.

21020019999973 is a deficient number, since it is larger than the sum of its proper divisors (1).

21020019999973 is an equidigital number, since it uses as much as digits as its factorization.

21020019999973 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4960116, while the sum is 61.

The spelling of 21020019999973 in words is "twenty-one trillion, twenty billion, nineteen million, nine hundred ninety-nine thousand, nine hundred seventy-three".