21623390 has 8 divisors (see below), whose sum is σ = 38922120. Its totient is φ = 8649352.

The previous prime is 21623389. The next prime is 21623411. The reversal of 21623390 is 9332612.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1081160 + ... + 1081179.

It is an arithmetic number, because the mean of its divisors is an integer number (4865265).

Almost surely, 2^21623390 is an apocalyptic number.

21623390 is a deficient number, since it is larger than the sum of its proper divisors (17298730).

21623390 is a wasteful number, since it uses less digits than its factorization.

21623390 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2162346.

The product of its (nonzero) digits is 1944, while the sum is 26.

The square root of 21623390 is about 4650.0956979400. The cubic root of 21623390 is about 278.5958185339.

The spelling of 21623390 in words is "twenty-one million, six hundred twenty-three thousand, three hundred ninety".