21280901 has 4 divisors (see below), whose sum is σ = 21580704. Its totient is φ = 20981100.

The previous prime is 21280891. The next prime is 21280907. The reversal of 21280901 is 10908212.

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 not a de Polignac number, because 21280901 - 2¹⁰ = 21279877 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21280907) 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, 149795 + ... + 149936.

It is an arithmetic number, because the mean of its divisors is an integer number (5395176).

Almost surely, 2^21280901 is an apocalyptic number.

It is an amenable number.

21280901 is a deficient number, since it is larger than the sum of its proper divisors (299803).

21280901 is an equidigital number, since it uses as much as digits as its factorization.

21280901 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 299802.

The product of its (nonzero) digits is 288, while the sum is 23.

The square root of 21280901 is about 4613.1226950949. The cubic root of 21280901 is about 277.1171074037.

The spelling of 21280901 in words is "twenty-one million, two hundred eighty thousand, nine hundred one".