21871801 has 4 divisors (see below), whose sum is σ = 24996352. Its totient is φ = 18747252.

The previous prime is 21871799. The next prime is 21871807. The reversal of 21871801 is 10817812.

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 21871801 - 2¹ = 21871799 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21871801.

It is not an unprimeable number, because it can be changed into a prime (21871807) 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, 1562265 + ... + 1562278.

It is an arithmetic number, because the mean of its divisors is an integer number (6249088).

Almost surely, 2^21871801 is an apocalyptic number.

It is an amenable number.

21871801 is a deficient number, since it is larger than the sum of its proper divisors (3124551).

21871801 is an equidigital number, since it uses as much as digits as its factorization.

21871801 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3124550.

The product of its (nonzero) digits is 896, while the sum is 28.

The square root of 21871801 is about 4676.7297334783. The cubic root of 21871801 is about 279.6586017665.

The spelling of 21871801 in words is "twenty-one million, eight hundred seventy-one thousand, eight hundred one".