21643061 has 8 divisors (see below), whose sum is σ = 24160224. Its totient is φ = 19217520.

The previous prime is 21643051. The next prime is 21643067. The reversal of 21643061 is 16034612.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21643061 - 2²² = 17448757 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21643067) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22406 + ... + 23351.

It is an arithmetic number, because the mean of its divisors is an integer number (3020028).

Almost surely, 2^21643061 is an apocalyptic number.

It is an amenable number.

21643061 is a deficient number, since it is larger than the sum of its proper divisors (2517163).

21643061 is a wasteful number, since it uses less digits than its factorization.

21643061 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45811.

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 21643061 is about 4652.2103348838. The cubic root of 21643061 is about 278.6802733360.

Adding to 21643061 its reverse (16034612), we get a palindrome (37677673).

It can be divided in two parts, 2164 and 3061, that added together give a palindrome (5225).

The spelling of 21643061 in words is "twenty-one million, six hundred forty-three thousand, sixty-one".