21651413 has 4 divisors (see below), whose sum is σ = 24744480. Its totient is φ = 18558348.

The previous prime is 21651391. The next prime is 21651419. The reversal of 21651413 is 31415612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21651413 - 2¹⁰ = 21650389 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21651419) 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, 1546523 + ... + 1546536.

It is an arithmetic number, because the mean of its divisors is an integer number (6186120).

Almost surely, 2^21651413 is an apocalyptic number.

It is an amenable number.

21651413 is a deficient number, since it is larger than the sum of its proper divisors (3093067).

21651413 is an equidigital number, since it uses as much as digits as its factorization.

21651413 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3093066.

The product of its digits is 720, while the sum is 23.

The square root of 21651413 is about 4653.1078861337. The cubic root of 21651413 is about 278.7161160527.

The spelling of 21651413 in words is "twenty-one million, six hundred fifty-one thousand, four hundred thirteen".