21942487 has 8 divisors (see below), whose sum is σ = 25395200. Its totient is φ = 18569304.

The previous prime is 21942469. The next prime is 21942491. The reversal of 21942487 is 78424912.

21942487 is nontrivially palindromic in base 12.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21942487 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 (21942457) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19287 + ... + 20392.

It is an arithmetic number, because the mean of its divisors is an integer number (3174400).

Almost surely, 2^21942487 is an apocalyptic number.

21942487 is a deficient number, since it is larger than the sum of its proper divisors (3452713).

21942487 is an equidigital number, since it uses as much as digits as its factorization.

21942487 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39765.

The product of its digits is 32256, while the sum is 37.

The square root of 21942487 is about 4684.2808412818. The cubic root of 21942487 is about 279.9595477275.

The spelling of 21942487 in words is "twenty-one million, nine hundred forty-two thousand, four hundred eighty-seven".