21351601 has 2 divisors, whose sum is σ = 21351602. Its totient is φ = 21351600.

The previous prime is 21351593. The next prime is 21351619. The reversal of 21351601 is 10615312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20711601 + 640000 = 4551^2 + 800^2 .

It is a cyclic number.

It is not a de Polignac number, because 21351601 - 2³ = 21351593 is a prime.

It is not a weakly prime, because it can be changed into another prime (21351661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10675800 + 10675801.

It is an arithmetic number, because the mean of its divisors is an integer number (10675801).

Almost surely, 2^21351601 is an apocalyptic number.

It is an amenable number.

21351601 is a deficient number, since it is larger than the sum of its proper divisors (1).

21351601 is an equidigital number, since it uses as much as digits as its factorization.

21351601 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 180, while the sum is 19.

The square root of 21351601 is about 4620.7792632845. The cubic root of 21351601 is about 277.4236502343.

Adding to 21351601 its reverse (10615312), we get a palindrome (31966913).

It can be divided in two parts, 21351 and 601, that added together give a cube (21952 = 28³).

The spelling of 21351601 in words is "twenty-one million, three hundred fifty-one thousand, six hundred one".