21355601 has 4 divisors (see below), whose sum is σ = 22479600. Its totient is φ = 20231604.

The previous prime is 21355591. The next prime is 21355627. The reversal of 21355601 is 10655312.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21355601 - 2¹⁰ = 21354577 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21355681) 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, 561971 + ... + 562008.

It is an arithmetic number, because the mean of its divisors is an integer number (5619900).

Almost surely, 2^21355601 is an apocalyptic number.

It is an amenable number.

21355601 is a deficient number, since it is larger than the sum of its proper divisors (1123999).

21355601 is a wasteful number, since it uses less digits than its factorization.

21355601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1123998.

The product of its (nonzero) digits is 900, while the sum is 23.

The square root of 21355601 is about 4621.2120704421. The cubic root of 21355601 is about 277.4409732961.

The spelling of 21355601 in words is "twenty-one million, three hundred fifty-five thousand, six hundred one".