21438790 has 16 divisors (see below), whose sum is σ = 38649312. Its totient is φ = 8562304.

The previous prime is 21438787. The next prime is 21438793. The reversal of 21438790 is 9783412.

It is an interprime number because it is at equal distance from previous prime (21438787) and next prime (21438793).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21438793) 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, 7662 + ... + 10078.

It is an arithmetic number, because the mean of its divisors is an integer number (2415582).

Almost surely, 2^21438790 is an apocalyptic number.

21438790 is a deficient number, since it is larger than the sum of its proper divisors (17210522).

21438790 is a wasteful number, since it uses less digits than its factorization.

21438790 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3311.

The product of its (nonzero) digits is 12096, while the sum is 34.

The square root of 21438790 is about 4630.2040991732. The cubic root of 21438790 is about 277.8007560843.

The spelling of 21438790 in words is "twenty-one million, four hundred thirty-eight thousand, seven hundred ninety".