21073501 has 4 divisors (see below), whose sum is σ = 21087004. Its totient is φ = 21060000.

The previous prime is 21073471. The next prime is 21073511. The reversal of 21073501 is 10537012.

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

It can be written as a sum of positive squares in 2 ways, for example, as 9308601 + 11764900 = 3051^2 + 3430^2 .

It is a cyclic number.

It is not a de Polignac number, because 21073501 - 2⁵ = 21073469 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21073511) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4050 + ... + 7651.

It is an arithmetic number, because the mean of its divisors is an integer number (5271751).

Almost surely, 2^21073501 is an apocalyptic number.

It is an amenable number.

21073501 is a deficient number, since it is larger than the sum of its proper divisors (13503).

21073501 is a wasteful number, since it uses less digits than its factorization.

21073501 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13502.

The product of its (nonzero) digits is 210, while the sum is 19.

The square root of 21073501 is about 4590.5883065246. The cubic root of 21073501 is about 276.2139217027.

The spelling of 21073501 in words is "twenty-one million, seventy-three thousand, five hundred one".