21783401 has 4 divisors (see below), whose sum is σ = 21861204. Its totient is φ = 21705600.

The previous prime is 21783397. The next prime is 21783431. The reversal of 21783401 is 10438712.

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 7728400 + 14055001 = 2780^2 + 3749^2 .

It is a cyclic number.

It is not a de Polignac number, because 21783401 - 2² = 21783397 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21783431) 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, 38480 + ... + 39041.

It is an arithmetic number, because the mean of its divisors is an integer number (5465301).

Almost surely, 2^21783401 is an apocalyptic number.

It is an amenable number.

21783401 is a deficient number, since it is larger than the sum of its proper divisors (77803).

21783401 is an equidigital number, since it uses as much as digits as its factorization.

21783401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77802.

The product of its (nonzero) digits is 1344, while the sum is 26.

The square root of 21783401 is about 4667.2691158749. The cubic root of 21783401 is about 279.2813244719.

The spelling of 21783401 in words is "twenty-one million, seven hundred eighty-three thousand, four hundred one".