21625939 has 2 divisors, whose sum is σ = 21625940. Its totient is φ = 21625938.

The previous prime is 21625913. The next prime is 21625949. The reversal of 21625939 is 93952612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21625939 - 2⁷ = 21625811 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21625898 and 21625907.

It is not a weakly prime, because it can be changed into another prime (21625949) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10812969 + 10812970.

It is an arithmetic number, because the mean of its divisors is an integer number (10812970).

Almost surely, 2^21625939 is an apocalyptic number.

21625939 is a deficient number, since it is larger than the sum of its proper divisors (1).

21625939 is an equidigital number, since it uses as much as digits as its factorization.

21625939 is an evil number, because the sum of its binary digits is even.

The product of its digits is 29160, while the sum is 37.

The square root of 21625939 is about 4650.3697702441. The cubic root of 21625939 is about 278.6067652115.

The spelling of 21625939 in words is "twenty-one million, six hundred twenty-five thousand, nine hundred thirty-nine".