21478554 has 16 divisors (see below), whose sum is σ = 47730240. Its totient is φ = 7159500.

The previous prime is 21478553. The next prime is 21478579. The reversal of 21478554 is 45587412.

It is a super-2 number, since 2×21478554² = 922656563861832, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21478553) 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, 198822 + ... + 198929.

It is an arithmetic number, because the mean of its divisors is an integer number (2983140).

Almost surely, 2^21478554 is an apocalyptic number.

21478554 is an abundant number, since it is smaller than the sum of its proper divisors (26251686).

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

21478554 is a wasteful number, since it uses less digits than its factorization.

21478554 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 397762 (or 397756 counting only the distinct ones).

The product of its digits is 44800, while the sum is 36.

The square root of 21478554 is about 4634.4960891126. The cubic root of 21478554 is about 277.9724020703.

It can be divided in two parts, 2147 and 8554, that added together give a palindrome (10701).

The spelling of 21478554 in words is "twenty-one million, four hundred seventy-eight thousand, five hundred fifty-four".