21871542 has 48 divisors (see below), whose sum is σ = 55518912. Its totient is φ = 5680080.

The previous prime is 21871541. The next prime is 21871543. The reversal of 21871542 is 24517812.

It is an interprime number because it is at equal distance from previous prime (21871541) and next prime (21871543).

It is a plaindrome in base 8.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21871541) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 148 + ... + 6615.

It is an arithmetic number, because the mean of its divisors is an integer number (1156644).

Almost surely, 2^21871542 is an apocalyptic number.

21871542 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 21871542, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27759456).

21871542 is an abundant number, since it is smaller than the sum of its proper divisors (33647370).

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

21871542 is a wasteful number, since it uses less digits than its factorization.

21871542 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6793 (or 6786 counting only the distinct ones).

The product of its digits is 4480, while the sum is 30.

The square root of 21871542 is about 4676.7020431069. The cubic root of 21871542 is about 279.6574978814.

The spelling of 21871542 in words is "twenty-one million, eight hundred seventy-one thousand, five hundred forty-two".