21716990 has 16 divisors (see below), whose sum is σ = 41390352. Its totient is φ = 8175744.

The previous prime is 21716977. The next prime is 21716999. The reversal of 21716990 is 9961712.

It is a zygodrome in base 9.

It is a self number, because there is not a number n which added to its sum of digits gives 21716990.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21716999) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 63704 + ... + 64043.

It is an arithmetic number, because the mean of its divisors is an integer number (2586897).

Almost surely, 2^21716990 is an apocalyptic number.

21716990 is a deficient number, since it is larger than the sum of its proper divisors (19673362).

21716990 is a wasteful number, since it uses less digits than its factorization.

21716990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 127771.

The product of its (nonzero) digits is 6804, while the sum is 35.

The square root of 21716990 is about 4660.1491392444. The cubic root of 21716990 is about 278.9972208028.

The spelling of 21716990 in words is "twenty-one million, seven hundred sixteen thousand, nine hundred ninety".