21016507 has 2 divisors, whose sum is σ = 21016508. Its totient is φ = 21016506.

The previous prime is 21016483. The next prime is 21016517. The reversal of 21016507 is 70561012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21016507 - 2¹¹ = 21014459 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is not a weakly prime, because it can be changed into another prime (21016517) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10508253 + 10508254.

It is an arithmetic number, because the mean of its divisors is an integer number (10508254).

Almost surely, 2^21016507 is an apocalyptic number.

21016507 is a deficient number, since it is larger than the sum of its proper divisors (1).

21016507 is an equidigital number, since it uses as much as digits as its factorization.

21016507 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 420, while the sum is 22.

The square root of 21016507 is about 4584.3764025219. The cubic root of 21016507 is about 275.9646868984.

Adding to 21016507 its reverse (70561012), we get a palindrome (91577519).

The spelling of 21016507 in words is "twenty-one million, sixteen thousand, five hundred seven".