21521142 has 24 divisors (see below), whose sum is σ = 46715760. Its totient is φ = 7160400.

The previous prime is 21521141. The next prime is 21521183. The reversal of 21521142 is 24112512.

21521142 is a `hidden beast` number, since 2 + 1 + 521 + 142 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21521141) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 15892 + ... + 17192.

It is an arithmetic number, because the mean of its divisors is an integer number (1946490).

Almost surely, 2^21521142 is an apocalyptic number.

21521142 is an abundant number, since it is smaller than the sum of its proper divisors (25194618).

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

21521142 is a wasteful number, since it uses less digits than its factorization.

21521142 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2228 (or 2225 counting only the distinct ones).

The product of its digits is 160, while the sum is 18.

The square root of 21521142 is about 4639.0884880545. The cubic root of 21521142 is about 278.1560033948.

Adding to 21521142 its reverse (24112512), we get a palindrome (45633654).

The spelling of 21521142 in words is "twenty-one million, five hundred twenty-one thousand, one hundred forty-two".