21500378 has 4 divisors (see below), whose sum is σ = 32250570. Its totient is φ = 10750188.

The previous prime is 21500321. The next prime is 21500429. The reversal of 21500378 is 87300512.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 20043529 + 1456849 = 4477^2 + 1207^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5375093 + ... + 5375096.

Almost surely, 2^21500378 is an apocalyptic number.

21500378 is a deficient number, since it is larger than the sum of its proper divisors (10750192).

21500378 is a wasteful number, since it uses less digits than its factorization.

21500378 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10750191.

The product of its (nonzero) digits is 1680, while the sum is 26.

The square root of 21500378 is about 4636.8500083570. The cubic root of 21500378 is about 278.0665179061.

The spelling of 21500378 in words is "twenty-one million, five hundred thousand, three hundred seventy-eight".