21780814 has 8 divisors (see below), whose sum is σ = 35641368. Its totient is φ = 9900360.

The previous prime is 21780809. The next prime is 21780823. The reversal of 21780814 is 41808712.

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

It is a congruent number.

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, 494997 + ... + 495040.

It is an arithmetic number, because the mean of its divisors is an integer number (4455171).

Almost surely, 2^21780814 is an apocalyptic number.

21780814 is a deficient number, since it is larger than the sum of its proper divisors (13860554).

21780814 is a wasteful number, since it uses less digits than its factorization.

21780814 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 990050.

The product of its (nonzero) digits is 3584, while the sum is 31.

The square root of 21780814 is about 4666.9919648527. The cubic root of 21780814 is about 279.2702682035.

The spelling of 21780814 in words is "twenty-one million, seven hundred eighty thousand, eight hundred fourteen".