21518601 has 12 divisors (see below), whose sum is σ = 31069008. Its totient is φ = 13241904.

The previous prime is 21518599. The next prime is 21518603. The reversal of 21518601 is 10681512.

It is an interprime number because it is at equal distance from previous prime (21518599) and next prime (21518603).

It is not a de Polignac number, because 21518601 - 2¹ = 21518599 is a prime.

It is a hoax number, since the sum of its digits (24) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21518603) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 20715 + ... + 21728.

It is an arithmetic number, because the mean of its divisors is an integer number (2589084).

Almost surely, 2^21518601 is an apocalyptic number.

It is an amenable number.

21518601 is a deficient number, since it is larger than the sum of its proper divisors (9550407).

21518601 is a wasteful number, since it uses less digits than its factorization.

21518601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42472 (or 42459 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 24.

The square root of 21518601 is about 4638.8146115145. The cubic root of 21518601 is about 278.1450556762.

The spelling of 21518601 in words is "twenty-one million, five hundred eighteen thousand, six hundred one".