21025019 has 2 divisors, whose sum is σ = 21025020. Its totient is φ = 21025018.

The previous prime is 21024961. The next prime is 21025021. The reversal of 21025019 is 91052012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21025019 - 2¹⁶ = 20959483 is a prime.

It is a super-2 number, since 2×21025019² = 884102847900722, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 21025021, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21025619) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10512509 + 10512510.

It is an arithmetic number, because the mean of its divisors is an integer number (10512510).

Almost surely, 2^21025019 is an apocalyptic number.

21025019 is a deficient number, since it is larger than the sum of its proper divisors (1).

21025019 is an equidigital number, since it uses as much as digits as its factorization.

21025019 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 180, while the sum is 20.

The square root of 21025019 is about 4585.3046790808. The cubic root of 21025019 is about 276.0019384797.

The spelling of 21025019 in words is "twenty-one million, twenty-five thousand, nineteen".