21501449 has 4 divisors (see below), whose sum is σ = 21698820. Its totient is φ = 21304080.

The previous prime is 21501401. The next prime is 21501451. The reversal of 21501449 is 94410512.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 11055625 + 10445824 = 3325^2 + 3232^2 .

It is a cyclic number.

It is not a de Polignac number, because 21501449 - 2²⁴ = 4724233 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21501479) 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, 98522 + ... + 98739.

It is an arithmetic number, because the mean of its divisors is an integer number (5424705).

Almost surely, 2^21501449 is an apocalyptic number.

It is an amenable number.

21501449 is a deficient number, since it is larger than the sum of its proper divisors (197371).

21501449 is a wasteful number, since it uses less digits than its factorization.

21501449 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 197370.

The product of its (nonzero) digits is 1440, while the sum is 26.

The square root of 21501449 is about 4636.9654948037. The cubic root of 21501449 is about 278.0711349458.

The spelling of 21501449 in words is "twenty-one million, five hundred one thousand, four hundred forty-nine".