21650939 has 2 divisors, whose sum is σ = 21650940. Its totient is φ = 21650938.

The previous prime is 21650917. The next prime is 21650947. The reversal of 21650939 is 93905612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21650939 - 2⁸ = 21650683 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21650899 and 21650908.

It is not a weakly prime, because it can be changed into another prime (21650999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10825469 + 10825470.

It is an arithmetic number, because the mean of its divisors is an integer number (10825470).

Almost surely, 2^21650939 is an apocalyptic number.

21650939 is a deficient number, since it is larger than the sum of its proper divisors (1).

21650939 is an equidigital number, since it uses as much as digits as its factorization.

21650939 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 14580, while the sum is 35.

The square root of 21650939 is about 4653.0569521552. The cubic root of 21650939 is about 278.7140821222.

The spelling of 21650939 in words is "twenty-one million, six hundred fifty thousand, nine hundred thirty-nine".