21420011 has 4 divisors (see below), whose sum is σ = 22547400. Its totient is φ = 20292624.

The previous prime is 21420001. The next prime is 21420013. The reversal of 21420011 is 11002412.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21420011 - 2¹⁰ = 21418987 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21419974 and 21420001.

It is not an unprimeable number, because it can be changed into a prime (21420013) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 563666 + ... + 563703.

It is an arithmetic number, because the mean of its divisors is an integer number (5636850).

Almost surely, 2^21420011 is an apocalyptic number.

21420011 is a deficient number, since it is larger than the sum of its proper divisors (1127389).

21420011 is a wasteful number, since it uses less digits than its factorization.

21420011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1127388.

The product of its (nonzero) digits is 16, while the sum is 11.

The square root of 21420011 is about 4628.1757745358. The cubic root of 21420011 is about 277.7196205299.

Adding to 21420011 its reverse (11002412), we get a palindrome (32422423).

The spelling of 21420011 in words is "twenty-one million, four hundred twenty thousand, eleven".