21402011 has 4 divisors (see below), whose sum is σ = 21721512. Its totient is φ = 21082512.

The previous prime is 21401993. The next prime is 21402013. The reversal of 21402011 is 11020412.

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 21402011 - 2¹⁴ = 21385627 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21401983 and 21402001.

It is not an unprimeable number, because it can be changed into a prime (21402013) 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, 159650 + ... + 159783.

It is an arithmetic number, because the mean of its divisors is an integer number (5430378).

Almost surely, 2^21402011 is an apocalyptic number.

21402011 is a deficient number, since it is larger than the sum of its proper divisors (319501).

21402011 is an equidigital number, since it uses as much as digits as its factorization.

21402011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 319500.

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

The square root of 21402011 is about 4626.2307551613. The cubic root of 21402011 is about 277.6418061582.

Adding to 21402011 its reverse (11020412), we get a palindrome (32422423).

The spelling of 21402011 in words is "twenty-one million, four hundred two thousand, eleven".