21416501 has 4 divisors (see below), whose sum is σ = 21439104. Its totient is φ = 21393900.

The previous prime is 21416491. The next prime is 21416503. The reversal of 21416501 is 10561412.

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 a de Polignac number, because none of the positive numbers 2^k-21416501 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21416503) 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, 9815 + ... + 11796.

It is an arithmetic number, because the mean of its divisors is an integer number (5359776).

Almost surely, 2^21416501 is an apocalyptic number.

It is an amenable number.

21416501 is a deficient number, since it is larger than the sum of its proper divisors (22603).

21416501 is an equidigital number, since it uses as much as digits as its factorization.

21416501 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22602.

The product of its (nonzero) digits is 240, while the sum is 20.

The square root of 21416501 is about 4627.7965599192. The cubic root of 21416501 is about 277.7044501499.

Adding to 21416501 its reverse (10561412), we get a palindrome (31977913).

The spelling of 21416501 in words is "twenty-one million, four hundred sixteen thousand, five hundred one".