21977378 has 4 divisors (see below), whose sum is σ = 32966070. Its totient is φ = 10988688.

The previous prime is 21977377. The next prime is 21977381. The reversal of 21977378 is 87377912.

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., 21967969 + 9409 = 4687^2 + 97^2 .

It is not an unprimeable number, because it can be changed into a prime (21977377) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5494343 + ... + 5494346.

Almost surely, 2^21977378 is an apocalyptic number.

21977378 is a deficient number, since it is larger than the sum of its proper divisors (10988692).

21977378 is a wasteful number, since it uses less digits than its factorization.

21977378 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10988691.

The product of its digits is 148176, while the sum is 44.

The square root of 21977378 is about 4688.0036262785. The cubic root of 21977378 is about 280.1078581068.

The spelling of 21977378 in words is "twenty-one million, nine hundred seventy-seven thousand, three hundred seventy-eight".