21572971 has 8 divisors (see below), whose sum is σ = 25228544. Its totient is φ = 18060840.

The previous prime is 21572933. The next prime is 21572981. The reversal of 21572971 is 17927512.

21572971 = T₂₁₈ + T₂₁₉ + ... + T₅₁₈.

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

It is not a de Polignac number, because 21572971 - 2¹³ = 21564779 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21572911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35535 + ... + 36136.

It is an arithmetic number, because the mean of its divisors is an integer number (3153568).

Almost surely, 2^21572971 is an apocalyptic number.

21572971 is a deficient number, since it is larger than the sum of its proper divisors (3655573).

21572971 is an equidigital number, since it uses as much as digits as its factorization.

21572971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71721.

The product of its digits is 8820, while the sum is 34.

The square root of 21572971 is about 4644.6712477849. The cubic root of 21572971 is about 278.3791171732.

The spelling of 21572971 in words is "twenty-one million, five hundred seventy-two thousand, nine hundred seventy-one".