20547421 has 4 divisors (see below), whose sum is σ = 21025312. Its totient is φ = 20069532.

The previous prime is 20547409. The next prime is 20547427. The reversal of 20547421 is 12474502.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12474502 = 2 ⋅6237251.

It is a cyclic number.

It is not a de Polignac number, because 20547421 - 2⁹ = 20546909 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 (20547427) 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, 238881 + ... + 238966.

It is an arithmetic number, because the mean of its divisors is an integer number (5256328).

Almost surely, 2^20547421 is an apocalyptic number.

It is an amenable number.

20547421 is a deficient number, since it is larger than the sum of its proper divisors (477891).

20547421 is an equidigital number, since it uses as much as digits as its factorization.

20547421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 477890.

The product of its (nonzero) digits is 2240, while the sum is 25.

The square root of 20547421 is about 4532.9263175128. The cubic root of 20547421 is about 273.8960525305.

The spelling of 20547421 in words is "twenty million, five hundred forty-seven thousand, four hundred twenty-one".