21554501 has 4 divisors (see below), whose sum is σ = 21763872. Its totient is φ = 21345132.

The previous prime is 21554497. The next prime is 21554509. The reversal of 21554501 is 10545512.

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 a cyclic number.

It is not a de Polignac number, because 21554501 - 2² = 21554497 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 (21554509) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 104531 + ... + 104736.

It is an arithmetic number, because the mean of its divisors is an integer number (5440968).

Almost surely, 2^21554501 is an apocalyptic number.

It is an amenable number.

21554501 is a deficient number, since it is larger than the sum of its proper divisors (209371).

21554501 is a wasteful number, since it uses less digits than its factorization.

21554501 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 209370.

The product of its (nonzero) digits is 1000, while the sum is 23.

The square root of 21554501 is about 4642.6825219909. The cubic root of 21554501 is about 278.2996484348.

The spelling of 21554501 in words is "twenty-one million, five hundred fifty-four thousand, five hundred one".