21778995 has 32 divisors (see below), whose sum is σ = 40803840. Its totient is φ = 9711360.

The previous prime is 21778993. The next prime is 21779003. The reversal of 21778995 is 59987712.

It is not a de Polignac number, because 21778995 - 2¹ = 21778993 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21778993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1776 + ... + 6834.

It is an arithmetic number, because the mean of its divisors is an integer number (1275120).

Almost surely, 2^21778995 is an apocalyptic number.

21778995 is a deficient number, since it is larger than the sum of its proper divisors (19024845).

21778995 is a wasteful number, since it uses less digits than its factorization.

21778995 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5115.

The product of its digits is 317520, while the sum is 48.

The square root of 21778995 is about 4666.7970815110. The cubic root of 21778995 is about 279.2624936737.

The spelling of 21778995 in words is "twenty-one million, seven hundred seventy-eight thousand, nine hundred ninety-five".