21020420249 has 2 divisors, whose sum is σ = 21020420250. Its totient is φ = 21020420248.

The previous prime is 21020420237. The next prime is 21020420261. The reversal of 21020420249 is 94202402012.

It is a happy number.

It is a balanced prime because it is at equal distance from previous prime (21020420237) and next prime (21020420261).

It can be written as a sum of positive squares in only one way, i.e., 13071806224 + 7948614025 = 114332^2 + 89155^2 .

It is a cyclic number.

It is not a de Polignac number, because 21020420249 - 2⁸ = 21020419993 is a prime.

It is not a weakly prime, because it can be changed into another prime (21020420549) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510210124 + 10510210125.

It is an arithmetic number, because the mean of its divisors is an integer number (10510210125).

Almost surely, 2^21020420249 is an apocalyptic number.

It is an amenable number.

21020420249 is a deficient number, since it is larger than the sum of its proper divisors (1).

21020420249 is an equidigital number, since it uses as much as digits as its factorization.

21020420249 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2304, while the sum is 26.

The spelling of 21020420249 in words is "twenty-one billion, twenty million, four hundred twenty thousand, two hundred forty-nine".