21901541 has 4 divisors (see below), whose sum is σ = 21955500. Its totient is φ = 21847584.

The previous prime is 21901519. The next prime is 21901571. The reversal of 21901541 is 14510912.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 8579041 + 13322500 = 2929^2 + 3650^2 .

It is a cyclic number.

It is not a de Polignac number, because 21901541 - 2²² = 17707237 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21901571) 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, 26366 + ... + 27183.

It is an arithmetic number, because the mean of its divisors is an integer number (5488875).

Almost surely, 2^21901541 is an apocalyptic number.

It is an amenable number.

21901541 is a deficient number, since it is larger than the sum of its proper divisors (53959).

21901541 is an equidigital number, since it uses as much as digits as its factorization.

21901541 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53958.

The product of its (nonzero) digits is 360, while the sum is 23.

The square root of 21901541 is about 4679.9082255959. The cubic root of 21901541 is about 279.7852988468.

The spelling of 21901541 in words is "twenty-one million, nine hundred one thousand, five hundred forty-one".