21520011 has 16 divisors (see below), whose sum is σ = 30477600. Its totient is φ = 13459968.

The previous prime is 21520003. The next prime is 21520013. The reversal of 21520011 is 11002512.

It is not a de Polignac number, because 21520011 - 2³ = 21520003 is a prime.

It is a super-2 number, since 2×21520011² = 926221746880242, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21520013) 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, 25545 + ... + 26373.

It is an arithmetic number, because the mean of its divisors is an integer number (1904850).

Almost surely, 2^21520011 is an apocalyptic number.

21520011 is a deficient number, since it is larger than the sum of its proper divisors (8957589).

21520011 is a wasteful number, since it uses less digits than its factorization.

21520011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1358.

The product of its (nonzero) digits is 20, while the sum is 12.

The square root of 21520011 is about 4638.9665875063. The cubic root of 21520011 is about 278.1511306678.

Adding to 21520011 its reverse (11002512), we get a palindrome (32522523).

The spelling of 21520011 in words is "twenty-one million, five hundred twenty thousand, eleven".