21150811 has 8 divisors (see below), whose sum is σ = 23107248. Its totient is φ = 19200000.

The previous prime is 21150809. The next prime is 21150817. The reversal of 21150811 is 11805112.

It is a happy number.

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

It is a 11-Lehmer number, since φ(21150811) divides (21150811-1)¹¹.

It is a cyclic number.

It is not a de Polignac number, because 21150811 - 2¹ = 21150809 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21150817) 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, 12411 + ... + 14011.

It is an arithmetic number, because the mean of its divisors is an integer number (2888406).

Almost surely, 2^21150811 is an apocalyptic number.

21150811 is a deficient number, since it is larger than the sum of its proper divisors (1956437).

21150811 is a wasteful number, since it uses less digits than its factorization.

21150811 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2813.

The product of its (nonzero) digits is 80, while the sum is 19.

The square root of 21150811 is about 4599.0010871927. The cubic root of 21150811 is about 276.5512812179.

Adding to 21150811 its reverse (11805112), we get a palindrome (32955923).

The spelling of 21150811 in words is "twenty-one million, one hundred fifty thousand, eight hundred eleven".