21554988 has 48 divisors (see below), whose sum is σ = 61904640. Its totient is φ = 5684544.

The previous prime is 21554983. The next prime is 21554993. The reversal of 21554988 is 88945512.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21554983) and next prime (21554993).

It is a Harshad number since it is a multiple of its sum of digits (42).

It is not an unprimeable number, because it can be changed into a prime (21554983) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8778 + ... + 10961.

It is an arithmetic number, because the mean of its divisors is an integer number (1289680).

Almost surely, 2^21554988 is an apocalyptic number.

21554988 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21554988 is an abundant number, since it is smaller than the sum of its proper divisors (40349652).

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

21554988 is a wasteful number, since it uses less digits than its factorization.

21554988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19766 (or 19764 counting only the distinct ones).

The product of its digits is 115200, while the sum is 42.

The square root of 21554988 is about 4642.7349698211. The cubic root of 21554988 is about 278.3017443762.

The spelling of 21554988 in words is "twenty-one million, five hundred fifty-four thousand, nine hundred eighty-eight".