21715401 has 4 divisors (see below), whose sum is σ = 28953872. Its totient is φ = 14476932.

The previous prime is 21715361. The next prime is 21715433. The reversal of 21715401 is 10451712.

It is a happy number.

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 not a de Polignac number, because 21715401 - 2¹⁴ = 21699017 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21715471) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3619231 + ... + 3619236.

It is an arithmetic number, because the mean of its divisors is an integer number (7238468).

Almost surely, 2^21715401 is an apocalyptic number.

It is an amenable number.

21715401 is a deficient number, since it is larger than the sum of its proper divisors (7238471).

21715401 is an equidigital number, since it uses as much as digits as its factorization.

21715401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7238470.

The product of its (nonzero) digits is 280, while the sum is 21.

The square root of 21715401 is about 4659.9786480198. The cubic root of 21715401 is about 278.9904160323.

It can be divided in two parts, 21 and 715401, that multiplied together give a triangular number (15023421 = T₅₄₈₁).

The spelling of 21715401 in words is "twenty-one million, seven hundred fifteen thousand, four hundred one".