21739087 has 4 divisors (see below), whose sum is σ = 21805096. Its totient is φ = 21673080.

The previous prime is 21739049. The next prime is 21739103. The reversal of 21739087 is 78093712.

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 21739087 - 2¹¹ = 21737039 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 (21739687) 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, 32508 + ... + 33169.

It is an arithmetic number, because the mean of its divisors is an integer number (5451274).

Almost surely, 2^21739087 is an apocalyptic number.

21739087 is a deficient number, since it is larger than the sum of its proper divisors (66009).

21739087 is an equidigital number, since it uses as much as digits as its factorization.

21739087 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66008.

The product of its (nonzero) digits is 21168, while the sum is 37.

The square root of 21739087 is about 4662.5193833377. The cubic root of 21739087 is about 279.0918151244.

It can be divided in two parts, 217 and 39087, that added together give a cube (39304 = 34³).

The spelling of 21739087 in words is "twenty-one million, seven hundred thirty-nine thousand, eighty-seven".