21377618 has 4 divisors (see below), whose sum is σ = 32066430. Its totient is φ = 10688808.

The previous prime is 21377599. The next prime is 21377627. The reversal of 21377618 is 81677312.

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., 18003049 + 3374569 = 4243^2 + 1837^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5344403 + ... + 5344406.

Almost surely, 2^21377618 is an apocalyptic number.

21377618 is a deficient number, since it is larger than the sum of its proper divisors (10688812).

21377618 is a wasteful number, since it uses less digits than its factorization.

21377618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10688811.

The product of its digits is 14112, while the sum is 35.

The square root of 21377618 is about 4623.5936240115. The cubic root of 21377618 is about 277.5362850586.

The spelling of 21377618 in words is "twenty-one million, three hundred seventy-seven thousand, six hundred eighteen".