21123011 has 16 divisors (see below), whose sum is σ = 26276544. Its totient is φ = 16533504.

The previous prime is 21122971. The next prime is 21123013. The reversal of 21123011 is 11032112.

It is not a de Polignac number, because 21123011 - 2²² = 16928707 is a prime.

It is a super-2 number, since 2×21123011² = 892363187412242, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21122983 and 21123001.

It is not an unprimeable number, because it can be changed into a prime (21123013) 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, 7631 + ... + 10023.

It is an arithmetic number, because the mean of its divisors is an integer number (1642284).

Almost surely, 2^21123011 is an apocalyptic number.

21123011 is a deficient number, since it is larger than the sum of its proper divisors (5153533).

21123011 is a wasteful number, since it uses less digits than its factorization.

21123011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2510.

The product of its (nonzero) digits is 12, while the sum is 11.

The square root of 21123011 is about 4595.9776979441. The cubic root of 21123011 is about 276.4300644881.

Adding to 21123011 its reverse (11032112), we get a palindrome (32155123).

The spelling of 21123011 in words is "twenty-one million, one hundred twenty-three thousand, eleven".