21820655 has 8 divisors (see below), whose sum is σ = 26209872. Its totient is φ = 17439808.

The previous prime is 21820633. The next prime is 21820661. The reversal of 21820655 is 55602812.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21820655 is a prime.

It is a super-2 number, since 2×21820655² = 952281969258050, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9059 + ... + 11211.

It is an arithmetic number, because the mean of its divisors is an integer number (3276234).

Almost surely, 2^21820655 is an apocalyptic number.

21820655 is a deficient number, since it is larger than the sum of its proper divisors (4389217).

21820655 is a wasteful number, since it uses less digits than its factorization.

21820655 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4185.

The product of its (nonzero) digits is 4800, while the sum is 29.

The square root of 21820655 is about 4671.2583957645. The cubic root of 21820655 is about 279.4404428899.

The spelling of 21820655 in words is "twenty-one million, eight hundred twenty thousand, six hundred fifty-five".