21253790 has 16 divisors (see below), whose sum is σ = 38419920. Its totient is φ = 8465280.

The previous prime is 21253763. The next prime is 21253849. The reversal of 21253790 is 9735212.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2000 + ... + 6819.

It is an arithmetic number, because the mean of its divisors is an integer number (2401245).

Almost surely, 2^21253790 is an apocalyptic number.

21253790 is a deficient number, since it is larger than the sum of its proper divisors (17166130).

21253790 is a wasteful number, since it uses less digits than its factorization.

21253790 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9067.

The product of its (nonzero) digits is 3780, while the sum is 29.

The square root of 21253790 is about 4610.1832935362. The cubic root of 21253790 is about 276.9993787646. Note that the first 3 decimals are identical.

The spelling of 21253790 in words is "twenty-one million, two hundred fifty-three thousand, seven hundred ninety".