21550011 has 16 divisors (see below), whose sum is σ = 34266624. Its totient is φ = 11778624.

The previous prime is 21550007. The next prime is 21550043. The reversal of 21550011 is 11005512.

It is not a de Polignac number, because 21550011 - 2² = 21550007 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21550811) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 21826 + ... + 22791.

It is an arithmetic number, because the mean of its divisors is an integer number (2141664).

Almost surely, 2^21550011 is an apocalyptic number.

21550011 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21550011 is a deficient number, since it is larger than the sum of its proper divisors (12716613).

21550011 is a wasteful number, since it uses less digits than its factorization.

21550011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44650.

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

The square root of 21550011 is about 4642.1989401576. The cubic root of 21550011 is about 278.2803229709.

Adding to 21550011 its reverse (11005512), we get a palindrome (32555523).

The spelling of 21550011 in words is "twenty-one million, five hundred fifty thousand, eleven".