21772378 has 4 divisors (see below), whose sum is σ = 32658570. Its totient is φ = 10886188.

The previous prime is 21772369. The next prime is 21772379. The reversal of 21772378 is 87327712.

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., 19775809 + 1996569 = 4447^2 + 1413^2 .

It is not an unprimeable number, because it can be changed into a prime (21772379) 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 as a sum of consecutive naturals, namely, 5443093 + ... + 5443096.

Almost surely, 2^21772378 is an apocalyptic number.

21772378 is a deficient number, since it is larger than the sum of its proper divisors (10886192).

21772378 is a wasteful number, since it uses less digits than its factorization.

21772378 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10886191.

The product of its digits is 32928, while the sum is 37.

The square root of 21772378 is about 4666.0880831806. The cubic root of 21772378 is about 279.2342085134.

The spelling of 21772378 in words is "twenty-one million, seven hundred seventy-two thousand, three hundred seventy-eight".