21010551 has 8 divisors (see below), whose sum is σ = 28610304. Its totient is φ = 13708920.

The previous prime is 21010547. The next prime is 21010553. The reversal of 21010551 is 15501012.

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

It is not a de Polignac number, because 21010551 - 2² = 21010547 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21010551.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21010553) 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 7 ways as a sum of consecutive naturals, for example, 74365 + ... + 74646.

It is an arithmetic number, because the mean of its divisors is an integer number (3576288).

Almost surely, 2^21010551 is an apocalyptic number.

21010551 is a deficient number, since it is larger than the sum of its proper divisors (7599753).

21010551 is a wasteful number, since it uses less digits than its factorization.

21010551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 149061.

The product of its (nonzero) digits is 50, while the sum is 15.

The square root of 21010551 is about 4583.7267588721. The cubic root of 21010551 is about 275.9386153131.

Adding to 21010551 its reverse (15501012), we get a palindrome (36511563).

The spelling of 21010551 in words is "twenty-one million, ten thousand, five hundred fifty-one".