55721420 has 24 divisors (see below), whose sum is σ = 117180000. Its totient is φ = 22257152.

The previous prime is 55721417. The next prime is 55721423. The reversal of 55721420 is 2412755.

It is an interprime number because it is at equal distance from previous prime (55721417) and next prime (55721423).

It is a self number, because there is not a number n which added to its sum of digits gives 55721420.

It is not an unprimeable number, because it can be changed into a prime (55721423) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17081 + ... + 20079.

It is an arithmetic number, because the mean of its divisors is an integer number (4882500).

Almost surely, 2^55721420 is an apocalyptic number.

It is an amenable number.

55721420 is an abundant number, since it is smaller than the sum of its proper divisors (61458580).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

55721420 is a wasteful number, since it uses less digits than its factorization.

55721420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3937 (or 3935 counting only the distinct ones).

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

The square root of 55721420 is about 7464.6781578311. The cubic root of 55721420 is about 381.9507716868.

The spelling of 55721420 in words is "fifty-five million, seven hundred twenty-one thousand, four hundred twenty".