21385601 has 4 divisors (see below), whose sum is σ = 21396804. Its totient is φ = 21374400.

The previous prime is 21385597. The next prime is 21385603. The reversal of 21385601 is 10658312.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 1893376 + 19492225 = 1376^2 + 4415^2 .

It is a cyclic number.

It is not a de Polignac number, because 21385601 - 2² = 21385597 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21385603) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1940 + ... + 6821.

It is an arithmetic number, because the mean of its divisors is an integer number (5349201).

Almost surely, 2^21385601 is an apocalyptic number.

It is an amenable number.

21385601 is a deficient number, since it is larger than the sum of its proper divisors (11203).

21385601 is an equidigital number, since it uses as much as digits as its factorization.

21385601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11202.

The product of its (nonzero) digits is 1440, while the sum is 26.

The square root of 21385601 is about 4624.4568329697. The cubic root of 21385601 is about 277.5708273610.

The spelling of 21385601 in words is "twenty-one million, three hundred eighty-five thousand, six hundred one".