21651055 has 8 divisors (see below), whose sum is σ = 26024544. Its totient is φ = 17292000.

The previous prime is 21651043. The next prime is 21651101. The reversal of 21651055 is 55015612.

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

It is a de Polignac number, because none of the positive numbers 2^k-21651055 is a prime.

It is a super-2 number, since 2×21651055² = 937536365226050, 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, 30 + ... + 6580.

It is an arithmetic number, because the mean of its divisors is an integer number (3253068).

Almost surely, 2^21651055 is an apocalyptic number.

21651055 is a deficient number, since it is larger than the sum of its proper divisors (4373489).

21651055 is an equidigital number, since it uses as much as digits as its factorization.

21651055 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7217.

The product of its (nonzero) digits is 1500, while the sum is 25.

The square root of 21651055 is about 4653.0694170622. The cubic root of 21651055 is about 278.7145798801.

Adding to 21651055 its reverse (55015612), we get a palindrome (76666667).

The spelling of 21651055 in words is "twenty-one million, six hundred fifty-one thousand, fifty-five".