21002390 has 8 divisors (see below), whose sum is σ = 37804320. Its totient is φ = 8400952.

The previous prime is 21002389. The next prime is 21002393. The reversal of 21002390 is 9320012.

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

It is a super-2 number, since 2×21002390² = 882200771424200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21002393) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1050110 + ... + 1050129.

It is an arithmetic number, because the mean of its divisors is an integer number (4725540).

Almost surely, 2^21002390 is an apocalyptic number.

21002390 is a deficient number, since it is larger than the sum of its proper divisors (16801930).

21002390 is a wasteful number, since it uses less digits than its factorization.

21002390 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2100246.

The product of its (nonzero) digits is 108, while the sum is 17.

The square root of 21002390 is about 4582.8364579156. The cubic root of 21002390 is about 275.9028836360.

The spelling of 21002390 in words is "twenty-one million, two thousand, three hundred ninety".