21365978 has 8 divisors (see below), whose sum is σ = 32069568. Its totient is φ = 10676124.

The previous prime is 21365947. The next prime is 21365987. The reversal of 21365978 is 87956312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2525 + ... + 7007.

It is an arithmetic number, because the mean of its divisors is an integer number (4008696).

Almost surely, 2^21365978 is an apocalyptic number.

21365978 is a deficient number, since it is larger than the sum of its proper divisors (10703590).

21365978 is a wasteful number, since it uses less digits than its factorization.

21365978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6868.

The product of its digits is 90720, while the sum is 41.

The square root of 21365978 is about 4622.3346914736. The cubic root of 21365978 is about 277.4859035666.

The spelling of 21365978 in words is "twenty-one million, three hundred sixty-five thousand, nine hundred seventy-eight".