21292718 has 4 divisors (see below), whose sum is σ = 31939080. Its totient is φ = 10646358.

The previous prime is 21292717. The next prime is 21292729. The reversal of 21292718 is 81729212.

It is a happy number.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21292717) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5323178 + ... + 5323181.

It is an arithmetic number, because the mean of its divisors is an integer number (7984770).

Almost surely, 2^21292718 is an apocalyptic number.

21292718 is a deficient number, since it is larger than the sum of its proper divisors (10646362).

21292718 is a wasteful number, since it uses less digits than its factorization.

21292718 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10646361.

The product of its digits is 4032, while the sum is 32.

The square root of 21292718 is about 4614.4033200404. The cubic root of 21292718 is about 277.1683910549.

The spelling of 21292718 in words is "twenty-one million, two hundred ninety-two thousand, seven hundred eighteen".