21061633 has 4 divisors (see below), whose sum is σ = 22170160. Its totient is φ = 19953108.

The previous prime is 21061619. The next prime is 21061639. The reversal of 21061633 is 33616012.

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 21061633 - 2²¹ = 18964481 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21061639) 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, 554235 + ... + 554272.

It is an arithmetic number, because the mean of its divisors is an integer number (5542540).

It is a Proth number, since it is equal to 2571 ⋅ 2¹³ + 1 and 2571 < 2¹³.

Almost surely, 2^21061633 is an apocalyptic number.

It is an amenable number.

21061633 is a deficient number, since it is larger than the sum of its proper divisors (1108527).

21061633 is a wasteful number, since it uses less digits than its factorization.

21061633 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1108526.

The product of its (nonzero) digits is 648, while the sum is 22.

The square root of 21061633 is about 4589.2954797006. The cubic root of 21061633 is about 276.1620600084.

Adding to 21061633 its reverse (33616012), we get a palindrome (54677645).

The spelling of 21061633 in words is "twenty-one million, sixty-one thousand, six hundred thirty-three".