21712487 has 4 divisors (see below), whose sum is σ = 21763296. Its totient is φ = 21661680.

The previous prime is 21712477. The next prime is 21712513. The reversal of 21712487 is 78421712.

It is a happy number.

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 21712487 - 2⁶ = 21712423 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 (21712477) 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, 24758 + ... + 25619.

It is an arithmetic number, because the mean of its divisors is an integer number (5440824).

Almost surely, 2^21712487 is an apocalyptic number.

21712487 is a deficient number, since it is larger than the sum of its proper divisors (50809).

21712487 is an equidigital number, since it uses as much as digits as its factorization.

21712487 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50808.

The product of its digits is 6272, while the sum is 32.

The square root of 21712487 is about 4659.6659751532. The cubic root of 21712487 is about 278.9779361885.

The spelling of 21712487 in words is "twenty-one million, seven hundred twelve thousand, four hundred eighty-seven".