21250418 has 12 divisors (see below), whose sum is σ = 37079982. Its totient is φ = 9107280.

The previous prime is 21250399. The next prime is 21250429. The reversal of 21250418 is 81405212.

It can be written as a sum of positive squares in only one way, i.e., 20133169 + 1117249 = 4487^2 + 1057^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21250393 and 21250402.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 108323 + ... + 108518.

Almost surely, 2^21250418 is an apocalyptic number.

21250418 is a deficient number, since it is larger than the sum of its proper divisors (15829564).

21250418 is a wasteful number, since it uses less digits than its factorization.

21250418 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 216857 (or 216850 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 23.

The square root of 21250418 is about 4609.8175668892. The cubic root of 21250418 is about 276.9847289648.

The spelling of 21250418 in words is "twenty-one million, two hundred fifty thousand, four hundred eighteen".