21613001 has 4 divisors (see below), whose sum is σ = 22884372. Its totient is φ = 20341632.

The previous prime is 21612991. The next prime is 21613003. The reversal of 21613001 is 10031612.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 10086976 + 11526025 = 3176^2 + 3395^2 .

It is a cyclic number.

It is not a de Polignac number, because 21613001 - 2¹⁰ = 21611977 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21613003) 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, 635660 + ... + 635693.

It is an arithmetic number, because the mean of its divisors is an integer number (5721093).

Almost surely, 2^21613001 is an apocalyptic number.

It is an amenable number.

21613001 is a deficient number, since it is larger than the sum of its proper divisors (1271371).

21613001 is a wasteful number, since it uses less digits than its factorization.

21613001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1271370.

The product of its (nonzero) digits is 36, while the sum is 14.

The square root of 21613001 is about 4648.9784899481. The cubic root of 21613001 is about 278.5511940846.

Adding to 21613001 its reverse (10031612), we get a palindrome (31644613).

The spelling of 21613001 in words is "twenty-one million, six hundred thirteen thousand, one".