21052090 has 8 divisors (see below), whose sum is σ = 37893780. Its totient is φ = 8420832.

The previous prime is 21052081. The next prime is 21052091. The reversal of 21052090 is 9025012.

It can be written as a sum of positive squares in 2 ways, for example, as 19456921 + 1595169 = 4411^2 + 1263^2 .

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

It is not an unprimeable number, because it can be changed into a prime (21052091) 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, 1052595 + ... + 1052614.

Almost surely, 2^21052090 is an apocalyptic number.

21052090 is a deficient number, since it is larger than the sum of its proper divisors (16841690).

21052090 is a wasteful number, since it uses less digits than its factorization.

21052090 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2105216.

The product of its (nonzero) digits is 180, while the sum is 19.

The square root of 21052090 is about 4588.2556598341. The cubic root of 21052090 is about 276.1203441441.

The spelling of 21052090 in words is "twenty-one million, fifty-two thousand, ninety".