21534501 has 16 divisors (see below), whose sum is σ = 29952000. Its totient is φ = 13745088.

The previous prime is 21534479. The next prime is 21534503. The reversal of 21534501 is 10543512.

It is not a de Polignac number, because 21534501 - 2⁶ = 21534437 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21534503) 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 15 ways as a sum of consecutive naturals, for example, 10075 + ... + 12023.

It is an arithmetic number, because the mean of its divisors is an integer number (1872000).

Almost surely, 2^21534501 is an apocalyptic number.

It is an amenable number.

21534501 is a deficient number, since it is larger than the sum of its proper divisors (8417499).

21534501 is a wasteful number, since it uses less digits than its factorization.

21534501 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2108.

The product of its (nonzero) digits is 600, while the sum is 21.

The square root of 21534501 is about 4640.5280949478. The cubic root of 21534501 is about 278.2135455310.

It can be divided in two parts, 215 and 34501, that added together give a triangular number (34716 = T₂₆₃).

The spelling of 21534501 in words is "twenty-one million, five hundred thirty-four thousand, five hundred one".