55807421 has 4 divisors (see below), whose sum is σ = 57105312. Its totient is φ = 54509532.

The previous prime is 55807403. The next prime is 55807429. The reversal of 55807421 is 12470855.

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: 12470855 = 5 ⋅2494171.

It is a cyclic number.

It is not a de Polignac number, because 55807421 - 2¹⁸ = 55545277 is a prime.

It is a super-2 number, since 2×55807421² = 6228936477342482, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55807429) 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, 648881 + ... + 648966.

It is an arithmetic number, because the mean of its divisors is an integer number (14276328).

Almost surely, 2^55807421 is an apocalyptic number.

It is an amenable number.

55807421 is a deficient number, since it is larger than the sum of its proper divisors (1297891).

55807421 is a wasteful number, since it uses less digits than its factorization.

55807421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1297890.

The product of its (nonzero) digits is 11200, while the sum is 32.

The square root of 55807421 is about 7470.4364664991. The cubic root of 55807421 is about 382.1471728996.

The spelling of 55807421 in words is "fifty-five million, eight hundred seven thousand, four hundred twenty-one".