21501994 has 16 divisors (see below), whose sum is σ = 33180840. Its totient is φ = 10445760.

The previous prime is 21501967. The next prime is 21502001. The reversal of 21501994 is 49910512.

It can be written as a sum of positive squares in 4 ways, for example, as 15563025 + 5938969 = 3945^2 + 2437^2 .

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, 10624 + ... + 12484.

Almost surely, 2^21501994 is an apocalyptic number.

21501994 is a deficient number, since it is larger than the sum of its proper divisors (11678846).

21501994 is a wasteful number, since it uses less digits than its factorization.

21501994 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2025.

The product of its (nonzero) digits is 3240, while the sum is 31.

The square root of 21501994 is about 4637.0242613124. The cubic root of 21501994 is about 278.0734843609.

The spelling of 21501994 in words is "twenty-one million, five hundred one thousand, nine hundred ninety-four".