21501416 has 8 divisors (see below), whose sum is σ = 40315170. Its totient is φ = 10750704.

The previous prime is 21501401. The next prime is 21501451. The reversal of 21501416 is 61410512.

It can be written as a sum of positive squares in only one way, i.e., 21436900 + 64516 = 4630^2 + 254^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1343831 + ... + 1343846.

Almost surely, 2^21501416 is an apocalyptic number.

It is an amenable number.

21501416 is a deficient number, since it is larger than the sum of its proper divisors (18813754).

21501416 is a wasteful number, since it uses less digits than its factorization.

21501416 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2687683 (or 2687679 counting only the distinct ones).

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

The square root of 21501416 is about 4636.9619364407. The cubic root of 21501416 is about 278.0709926863.

Adding to 21501416 its reverse (61410512), we get a palindrome (82911928).

The spelling of 21501416 in words is "twenty-one million, five hundred one thousand, four hundred sixteen".