21420663 has 16 divisors (see below), whose sum is σ = 32990976. Its totient is φ = 12218240.

The previous prime is 21420661. The next prime is 21420667. The reversal of 21420663 is 36602412.

It is not a de Polignac number, because 21420663 - 2¹ = 21420661 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21420661) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 18531 + ... + 19652.

It is an arithmetic number, because the mean of its divisors is an integer number (2061936).

Almost surely, 2^21420663 is an apocalyptic number.

21420663 is a deficient number, since it is larger than the sum of its proper divisors (11570313).

21420663 is a wasteful number, since it uses less digits than its factorization.

21420663 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38214.

The product of its (nonzero) digits is 1728, while the sum is 24.

The square root of 21420663 is about 4628.2462121197. The cubic root of 21420663 is about 277.7224383211.

The spelling of 21420663 in words is "twenty-one million, four hundred twenty thousand, six hundred sixty-three".