55720421 has 4 divisors (see below), whose sum is σ = 58143072. Its totient is φ = 53297772.

The previous prime is 55720403. The next prime is 55720471. The reversal of 55720421 is 12402755.

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: 12402755 = 5 ⋅2480551.

It is a cyclic number.

It is not a de Polignac number, because 55720421 - 2²² = 51526117 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55720471) 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, 1211291 + ... + 1211336.

It is an arithmetic number, because the mean of its divisors is an integer number (14535768).

Almost surely, 2^55720421 is an apocalyptic number.

It is an amenable number.

55720421 is a deficient number, since it is larger than the sum of its proper divisors (2422651).

55720421 is a wasteful number, since it uses less digits than its factorization.

55720421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2422650.

The product of its (nonzero) digits is 2800, while the sum is 26.

The square root of 55720421 is about 7464.6112423890. The cubic root of 55720421 is about 381.9484890751.

The spelling of 55720421 in words is "fifty-five million, seven hundred twenty thousand, four hundred twenty-one".