21623217420 has 48 divisors (see below), whose sum is σ = 69194297088. Its totient is φ = 4942449600.

The previous prime is 21623217391. The next prime is 21623217437. The reversal of 21623217420 is 2471232612.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 25741506 + ... + 25742345.

It is an arithmetic number, because the mean of its divisors is an integer number (1441547856).

Almost surely, 2^21623217420 is an apocalyptic number.

21623217420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21623217420 is an abundant number, since it is smaller than the sum of its proper divisors (47571079668).

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

21623217420 is a wasteful number, since it uses less digits than its factorization.

21623217420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51483870 (or 51483868 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 30.

The spelling of 21623217420 in words is "twenty-one billion, six hundred twenty-three million, two hundred seventeen thousand, four hundred twenty".