21042177408 has 640 divisors, whose sum is σ = 74989992000. Its totient is φ = 5852528640.

The previous prime is 21042177353. The next prime is 21042177421. The reversal of 21042177408 is 80477124012.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 216929616 + ... + 216929712.

Almost surely, 2^21042177408 is an apocalyptic number.

21042177408 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21042177408, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37494996000).

21042177408 is an abundant number, since it is smaller than the sum of its proper divisors (53947814592).

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

21042177408 is an frugal number, since it uses more digits than its factorization.

21042177408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 205 (or 170 counting only the distinct ones).

The product of its (nonzero) digits is 25088, while the sum is 36.

The spelling of 21042177408 in words is "twenty-one billion, forty-two million, one hundred seventy-seven thousand, four hundred eight".