21051707 has 2 divisors, whose sum is σ = 21051708. Its totient is φ = 21051706.

The previous prime is 21051703. The next prime is 21051721. The reversal of 21051707 is 70715012.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21051707 - 2² = 21051703 is a prime.

It is a super-2 number, since 2×21051707² = 886348735227698, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21051703) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10525853 + 10525854.

It is an arithmetic number, because the mean of its divisors is an integer number (10525854).

Almost surely, 2^21051707 is an apocalyptic number.

21051707 is a deficient number, since it is larger than the sum of its proper divisors (1).

21051707 is an equidigital number, since it uses as much as digits as its factorization.

21051707 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 490, while the sum is 23.

The square root of 21051707 is about 4588.2139226501. The cubic root of 21051707 is about 276.1186696511.

Adding to 21051707 its reverse (70715012), we get a palindrome (91766719).

The spelling of 21051707 in words is "twenty-one million, fifty-one thousand, seven hundred seven".