21801385 has 16 divisors (see below), whose sum is σ = 26801280. Its totient is φ = 17019520.

The previous prime is 21801383. The next prime is 21801407. The reversal of 21801385 is 58310812.

21801385 = T₈₃₀ + T₈₃₁ + ... + T₈₈₈.

It is not a de Polignac number, because 21801385 - 2¹ = 21801383 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21801383) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 77445 + ... + 77725.

It is an arithmetic number, because the mean of its divisors is an integer number (1675080).

Almost surely, 2^21801385 is an apocalyptic number.

It is an amenable number.

21801385 is a deficient number, since it is larger than the sum of its proper divisors (4999895).

21801385 is a wasteful number, since it uses less digits than its factorization.

21801385 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 608.

The product of its (nonzero) digits is 1920, while the sum is 28.

The square root of 21801385 is about 4669.1953268202. The cubic root of 21801385 is about 279.3581599453.

The spelling of 21801385 in words is "twenty-one million, eight hundred one thousand, three hundred eighty-five".