21170651 has 2 divisors, whose sum is σ = 21170652. Its totient is φ = 21170650.

The previous prime is 21170647. The next prime is 21170671. The reversal of 21170651 is 15607112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21170651 - 2² = 21170647 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (21170641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10585325 + 10585326.

It is an arithmetic number, because the mean of its divisors is an integer number (10585326).

Almost surely, 2^21170651 is an apocalyptic number.

21170651 is a deficient number, since it is larger than the sum of its proper divisors (1).

21170651 is an equidigital number, since it uses as much as digits as its factorization.

21170651 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 23.

The square root of 21170651 is about 4601.1575717421. The cubic root of 21170651 is about 276.6377249124.

Adding to 21170651 its reverse (15607112), we get a palindrome (36777763).

The spelling of 21170651 in words is "twenty-one million, one hundred seventy thousand, six hundred fifty-one".