21555071 has 8 divisors (see below), whose sum is σ = 22778880. Its totient is φ = 20355192.

The previous prime is 21555067. The next prime is 21555097. The reversal of 21555071 is 17055512.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21555071 - 2² = 21555067 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21555071.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21555041) 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, 4115 + ... + 7748.

It is an arithmetic number, because the mean of its divisors is an integer number (2847360).

Almost surely, 2^21555071 is an apocalyptic number.

21555071 is a deficient number, since it is larger than the sum of its proper divisors (1223809).

21555071 is a wasteful number, since it uses less digits than its factorization.

21555071 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11965.

The product of its (nonzero) digits is 1750, while the sum is 26.

The square root of 21555071 is about 4642.7439085093. The cubic root of 21555071 is about 278.3021015868.

The spelling of 21555071 in words is "twenty-one million, five hundred fifty-five thousand, seventy-one".