21534787 has 4 divisors (see below), whose sum is σ = 22035640. Its totient is φ = 21033936.

The previous prime is 21534763. The next prime is 21534827. The reversal of 21534787 is 78743512.

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

It is a cyclic number.

It is not a de Polignac number, because 21534787 - 2⁷ = 21534659 is a prime.

It is a super-2 number, since 2×21534787² = 927494102270738, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21534727) 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, 250362 + ... + 250447.

It is an arithmetic number, because the mean of its divisors is an integer number (5508910).

Almost surely, 2^21534787 is an apocalyptic number.

21534787 is a deficient number, since it is larger than the sum of its proper divisors (500853).

21534787 is an equidigital number, since it uses as much as digits as its factorization.

21534787 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 500852.

The product of its digits is 47040, while the sum is 37.

The square root of 21534787 is about 4640.5589103038. The cubic root of 21534787 is about 278.2147771782.

The spelling of 21534787 in words is "twenty-one million, five hundred thirty-four thousand, seven hundred eighty-seven".