21750506 has 4 divisors (see below), whose sum is σ = 32625762. Its totient is φ = 10875252.

The previous prime is 21750503. The next prime is 21750523. The reversal of 21750506 is 60505712.

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., 18361225 + 3389281 = 4285^2 + 1841^2 .

It is a super-2 number, since 2×21750506² = 946169022512072, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21750503) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5437625 + ... + 5437628.

Almost surely, 2^21750506 is an apocalyptic number.

21750506 is a deficient number, since it is larger than the sum of its proper divisors (10875256).

21750506 is a wasteful number, since it uses less digits than its factorization.

21750506 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10875255.

The product of its (nonzero) digits is 2100, while the sum is 26.

The square root of 21750506 is about 4663.7437751232. The cubic root of 21750506 is about 279.1406732264.

The spelling of 21750506 in words is "twenty-one million, seven hundred fifty thousand, five hundred six".