21351708 has 96 divisors (see below), whose sum is σ = 64440320. Its totient is φ = 5987520.

The previous prime is 21351679. The next prime is 21351709. The reversal of 21351708 is 80715312.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21351709) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 45885 + ... + 46347.

Almost surely, 2^21351708 is an apocalyptic number.

21351708 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 21351708, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32220160).

21351708 is an abundant number, since it is smaller than the sum of its proper divisors (43088612).

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

21351708 is a wasteful number, since it uses less digits than its factorization.

21351708 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 544 (or 536 counting only the distinct ones).

The product of its (nonzero) digits is 1680, while the sum is 27.

The square root of 21351708 is about 4620.7908414037. The cubic root of 21351708 is about 277.4241136544.

The spelling of 21351708 in words is "twenty-one million, three hundred fifty-one thousand, seven hundred eight".