21506968 has 32 divisors (see below), whose sum is σ = 46726560. Its totient is φ = 9089280.

The previous prime is 21506941. The next prime is 21506971. The reversal of 21506968 is 86960512.

It is a Smith number, since the sum of its digits (37) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1458 + ... + 6718.

It is an arithmetic number, because the mean of its divisors is an integer number (1460205).

Almost surely, 2^21506968 is an apocalyptic number.

21506968 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 21506968, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23363280).

21506968 is an abundant number, since it is smaller than the sum of its proper divisors (25219592).

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

21506968 is a wasteful number, since it uses less digits than its factorization.

21506968 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5347 (or 5343 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 37.

The square root of 21506968 is about 4637.5605656422. The cubic root of 21506968 is about 278.0949247115.

The spelling of 21506968 in words is "twenty-one million, five hundred six thousand, nine hundred sixty-eight".