21371742 has 96 divisors (see below), whose sum is σ = 56881440. Its totient is φ = 5927040.

The previous prime is 21371717. The next prime is 21371759. The reversal of 21371742 is 24717312.

It is a happy number.

It is a super-2 number, since 2×21371742² = 913502712229128, which contains 22 as substring.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 108388 + ... + 108584.

It is an arithmetic number, because the mean of its divisors is an integer number (592515).

Almost surely, 2^21371742 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21371742, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28440720).

21371742 is an abundant number, since it is smaller than the sum of its proper divisors (35509698).

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

21371742 is a wasteful number, since it uses less digits than its factorization.

21371742 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 263 (or 250 counting only the distinct ones).

The product of its digits is 2352, while the sum is 27.

The square root of 21371742 is about 4622.9581438728. The cubic root of 21371742 is about 277.5108542139.

The spelling of 21371742 in words is "twenty-one million, three hundred seventy-one thousand, seven hundred forty-two".