21610947 has 4 divisors (see below), whose sum is σ = 28814600. Its totient is φ = 14407296.

The previous prime is 21610943. The next prime is 21610949. The reversal of 21610947 is 74901612.

It is a happy number.

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

It is not a de Polignac number, because 21610947 - 2² = 21610943 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21610943) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3601822 + ... + 3601827.

It is an arithmetic number, because the mean of its divisors is an integer number (7203650).

Almost surely, 2^21610947 is an apocalyptic number.

21610947 is a deficient number, since it is larger than the sum of its proper divisors (7203653).

21610947 is an equidigital number, since it uses as much as digits as its factorization.

21610947 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7203652.

The product of its (nonzero) digits is 3024, while the sum is 30.

The square root of 21610947 is about 4648.7575759551. The cubic root of 21610947 is about 278.5423697311.

The spelling of 21610947 in words is "twenty-one million, six hundred ten thousand, nine hundred forty-seven".