21418987 has 2 divisors, whose sum is σ = 21418988. Its totient is φ = 21418986.

The previous prime is 21418951. The next prime is 21419009. The reversal of 21418987 is 78981412.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21418987 - 2¹⁵ = 21386219 is a prime.

It is a Chen prime.

It is an alternating number because its digits alternate between even and odd.

It is not a weakly prime, because it can be changed into another prime (21418937) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10709493 + 10709494.

It is an arithmetic number, because the mean of its divisors is an integer number (10709494).

Almost surely, 2^21418987 is an apocalyptic number.

21418987 is a deficient number, since it is larger than the sum of its proper divisors (1).

21418987 is an equidigital number, since it uses as much as digits as its factorization.

21418987 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 32256, while the sum is 40.

The square root of 21418987 is about 4628.0651464732. The cubic root of 21418987 is about 277.7151949264.

The spelling of 21418987 in words is "twenty-one million, four hundred eighteen thousand, nine hundred eighty-seven".