21904541 has 4 divisors (see below), whose sum is σ = 22659900. Its totient is φ = 21149184.

The previous prime is 21904523. The next prime is 21904559. The reversal of 21904541 is 14540912.

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

It is an interprime number because it is at equal distance from previous prime (21904523) and next prime (21904559).

It can be written as a sum of positive squares in 2 ways, for example, as 14092516 + 7812025 = 3754^2 + 2795^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21904541 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21904541.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21904241) 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, 377636 + ... + 377693.

It is an arithmetic number, because the mean of its divisors is an integer number (5664975).

Almost surely, 2^21904541 is an apocalyptic number.

It is an amenable number.

21904541 is a deficient number, since it is larger than the sum of its proper divisors (755359).

21904541 is an equidigital number, since it uses as much as digits as its factorization.

21904541 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 755358.

The product of its (nonzero) digits is 1440, while the sum is 26.

The square root of 21904541 is about 4680.2287337266. The cubic root of 21904541 is about 279.7980729491.

The spelling of 21904541 in words is "twenty-one million, nine hundred four thousand, five hundred forty-one".