55721478 has 16 divisors (see below), whose sum is σ = 117998640. Its totient is φ = 17481216.

The previous prime is 55721473. The next prime is 55721483. The reversal of 55721478 is 87412755.

It is an interprime number because it is at equal distance from previous prime (55721473) and next prime (55721483).

It is a super-2 number, since 2×55721478² = 6209766221008968, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55721473) 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, 273043 + ... + 273246.

It is an arithmetic number, because the mean of its divisors is an integer number (7374915).

Almost surely, 2^55721478 is an apocalyptic number.

55721478 is an abundant number, since it is smaller than the sum of its proper divisors (62277162).

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

55721478 is a wasteful number, since it uses less digits than its factorization.

55721478 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 546311.

The product of its digits is 78400, while the sum is 39.

The square root of 55721478 is about 7464.6820427932. The cubic root of 55721478 is about 381.9509042100.

The spelling of 55721478 in words is "fifty-five million, seven hundred twenty-one thousand, four hundred seventy-eight".