21778994 has 8 divisors (see below), whose sum is σ = 32974128. Its totient is φ = 10787620.

The previous prime is 21778993. The next prime is 21779003. The reversal of 21778994 is 49987712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (21778993) 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, 50672 + ... + 51099.

It is an arithmetic number, because the mean of its divisors is an integer number (4121766).

Almost surely, 2^21778994 is an apocalyptic number.

21778994 is a deficient number, since it is larger than the sum of its proper divisors (11195134).

21778994 is a wasteful number, since it uses less digits than its factorization.

21778994 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 101880.

The product of its digits is 254016, while the sum is 47.

The square root of 21778994 is about 4666.7969743712. The cubic root of 21778994 is about 279.2624893995.

The spelling of 21778994 in words is "twenty-one million, seven hundred seventy-eight thousand, nine hundred ninety-four".