21349878 has 32 divisors (see below), whose sum is σ = 47354112. Its totient is φ = 6362400.

The previous prime is 21349877. The next prime is 21349907. The reversal of 21349878 is 87894312.

It is a super-2 number, since 2×21349878² = 911634581229768, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21349871) 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, 1375 + ... + 6677.

It is an arithmetic number, because the mean of its divisors is an integer number (1479816).

Almost surely, 2^21349878 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21349878, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23677056).

21349878 is an abundant number, since it is smaller than the sum of its proper divisors (26004234).

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

21349878 is a wasteful number, since it uses less digits than its factorization.

21349878 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5380.

The product of its digits is 96768, while the sum is 42.

The square root of 21349878 is about 4620.5928191088. The cubic root of 21349878 is about 277.4161876587.

The spelling of 21349878 in words is "twenty-one million, three hundred forty-nine thousand, eight hundred seventy-eight".