20738521 has 4 divisors (see below), whose sum is σ = 21958452. Its totient is φ = 19518592.

The previous prime is 20738507. The next prime is 20738533. The reversal of 20738521 is 12583702.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12583702 = 2 ⋅6291851.

It can be written as a sum of positive squares in 2 ways, for example, as 7778521 + 12960000 = 2789^2 + 3600^2 .

It is a cyclic number.

It is not a de Polignac number, because 20738521 - 2⁵ = 20738489 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20738521.

It is not an unprimeable number, because it can be changed into a prime (20738581) 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, 609940 + ... + 609973.

It is an arithmetic number, because the mean of its divisors is an integer number (5489613).

Almost surely, 2^20738521 is an apocalyptic number.

It is an amenable number.

20738521 is a deficient number, since it is larger than the sum of its proper divisors (1219931).

20738521 is a wasteful number, since it uses less digits than its factorization.

20738521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1219930.

The product of its (nonzero) digits is 3360, while the sum is 28.

The square root of 20738521 is about 4553.9566313262. The cubic root of 20738521 is about 274.7425513442.

The spelling of 20738521 in words is "twenty million, seven hundred thirty-eight thousand, five hundred twenty-one".