21775994 has 4 divisors (see below), whose sum is σ = 32663994. Its totient is φ = 10887996.

The previous prime is 21775991. The next prime is 21776011. The reversal of 21775994 is 49957712.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 13579225 + 8196769 = 3685^2 + 2863^2 .

It is not an unprimeable number, because it can be changed into a prime (21775991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5443997 + ... + 5444000.

Almost surely, 2^21775994 is an apocalyptic number.

21775994 is a deficient number, since it is larger than the sum of its proper divisors (10888000).

21775994 is a wasteful number, since it uses less digits than its factorization.

21775994 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10887999.

The product of its digits is 158760, while the sum is 44.

The square root of 21775994 is about 4666.4755437053. The cubic root of 21775994 is about 279.2496662492.

The spelling of 21775994 in words is "twenty-one million, seven hundred seventy-five thousand, nine hundred ninety-four".