21302990 has 16 divisors (see below), whose sum is σ = 40363920. Its totient is φ = 8072640.

The previous prime is 21302947. The next prime is 21302993. The reversal of 21302990 is 9920312.

21302990 = 185² + 186² + ... + 412².

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21302993) 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, 55871 + ... + 56250.

It is an arithmetic number, because the mean of its divisors is an integer number (2522745).

Almost surely, 2^21302990 is an apocalyptic number.

21302990 is a deficient number, since it is larger than the sum of its proper divisors (19060930).

21302990 is a wasteful number, since it uses less digits than its factorization.

21302990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 112147.

The product of its (nonzero) digits is 972, while the sum is 26.

The square root of 21302990 is about 4615.5162224826. The cubic root of 21302990 is about 277.2129542715.

The spelling of 21302990 in words is "twenty-one million, three hundred two thousand, nine hundred ninety".