21397140 has 36 divisors (see below), whose sum is σ = 64905204. Its totient is φ = 5705856.

The previous prime is 21397139. The next prime is 21397171. The reversal of 21397140 is 4179312.

It can be written as a sum of positive squares in 2 ways, for example, as 11737476 + 9659664 = 3426^2 + 3108^2 .

It is a tau number, because it is divible by the number of its divisors (36).

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 11 ways as a sum of consecutive naturals, for example, 59257 + ... + 59616.

Almost surely, 2^21397140 is an apocalyptic number.

21397140 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21397140 is an abundant number, since it is smaller than the sum of its proper divisors (43508064).

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

21397140 is a wasteful number, since it uses less digits than its factorization.

21397140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 118888 (or 118883 counting only the distinct ones).

The product of its (nonzero) digits is 1512, while the sum is 27.

The square root of 21397140 is about 4625.7042707030. The cubic root of 21397140 is about 277.6207412242.

The spelling of 21397140 in words is "twenty-one million, three hundred ninety-seven thousand, one hundred forty".