21601065 has 16 divisors (see below), whose sum is σ = 35036928. Its totient is φ = 11362176.

The previous prime is 21601061. The next prime is 21601121. The reversal of 21601065 is 56010612.

It is a happy number.

It is not a de Polignac number, because 21601065 - 2² = 21601061 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21601061) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8769 + ... + 10958.

It is an arithmetic number, because the mean of its divisors is an integer number (2189808).

Almost surely, 2^21601065 is an apocalyptic number.

It is an amenable number.

21601065 is a deficient number, since it is larger than the sum of its proper divisors (13435863).

21601065 is a wasteful number, since it uses less digits than its factorization.

21601065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19808.

The product of its (nonzero) digits is 360, while the sum is 21.

The square root of 21601065 is about 4647.6945897940. The cubic root of 21601065 is about 278.4999070639.

Adding to 21601065 its reverse (56010612), we get a palindrome (77611677).

The spelling of 21601065 in words is "twenty-one million, six hundred one thousand, sixty-five".