21297601 has 16 divisors (see below), whose sum is σ = 23623488. Its totient is φ = 19080000.

The previous prime is 21297569. The next prime is 21297631. The reversal of 21297601 is 10679212.

It is a happy number.

21297601 is a nontrivial binomial coefficient, being equal to C(6527, 2).

It is a cyclic number.

It is not a de Polignac number, because 21297601 - 2⁵ = 21297569 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21297601.

It is not an unprimeable number, because it can be changed into a prime (21297631) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 84726 + ... + 84976.

It is an arithmetic number, because the mean of its divisors is an integer number (1476468).

Almost surely, 2^21297601 is an apocalyptic number.

21297601 is the 6526-th triangular number.

21297601 is the 2176-th centered nonagonal number.

It is an amenable number.

21297601 is a deficient number, since it is larger than the sum of its proper divisors (2325887).

21297601 is a wasteful number, since it uses less digits than its factorization.

21297601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 432.

The product of its (nonzero) digits is 1512, while the sum is 28.

The square root of 21297601 is about 4614.9323938710. The cubic root of 21297601 is about 277.1895768552.

It can be divided in two parts, 2129 and 7601, that added together give a triangular number (9730 = T₁₃₉).

The spelling of 21297601 in words is "twenty-one million, two hundred ninety-seven thousand, six hundred one".