21500771 has 4 divisors (see below), whose sum is σ = 21513000. Its totient is φ = 21488544.

The previous prime is 21500753. The next prime is 21500783. The reversal of 21500771 is 17700512.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21500771 - 2⁶ = 21500707 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21500711) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2921 + ... + 7178.

It is an arithmetic number, because the mean of its divisors is an integer number (5378250).

Almost surely, 2^21500771 is an apocalyptic number.

21500771 is a deficient number, since it is larger than the sum of its proper divisors (12229).

21500771 is a wasteful number, since it uses less digits than its factorization.

21500771 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12228.

The product of its (nonzero) digits is 490, while the sum is 23.

The square root of 21500771 is about 4636.8923860707. The cubic root of 21500771 is about 278.0682121317.

The spelling of 21500771 in words is "twenty-one million, five hundred thousand, seven hundred seventy-one".